UNIX
Commands
1) ^D -
indicates end of data stream; can log a user off. The latter is disabled on
many systems
^C -
interrupt
^U
-Control-U is normally the "line-kill" signal for your terminal. When
typed it erases the entire input
logout -
leave the system
exit -
leave the shell
-----------------------------------------------------------------------------------------------------------------------------------------
2) id
id
- return user identity
You can
determine your userid and the list of groups you belong to with the id and
groups commands.
The
format in which we get as o/p is
"uid=%u(%s) gid=%u(%s)\n" <real user ID>, <user-name>,
<real group ID>, <group-name>
eg :
$ id
uid=1005(tibadmin)
gid=1(other)
$ id -a (
Reports user name, user ID and all the groups to which the
user belongs.)
uid=1005(tibadmin)
gid=1(other) groups=1(other)
------------------------------------------------------------------------------------------------------------------------------------------
3) man
The Unix
manual, usually called man pages, is available on-line to explain the usage of
the Unix system and commands.
Syntax
man
[options] command_name
------------------------------------------------------------------------------------------------------------------------------------------
4) cd
[directory] ---change directory
You can
change to a new directory with the cd command. cd will accept both absolute and
relative path names.
cd
-----changes to user's home directory
cd /
---changes directory to the system's root
cd ..
---goes up one directory level
cd ../..
--goes up two directory levels
cd
/full/path/name/from/root changes directory to absolute path named (note the
leading slash)
cd
path/from/current/location changes directory to path relative to current
location (no leading
slash)
cd
~--------username/directory changes directory to the named username's indicated
directory
------------------------------------------------------------------------------------------------------------------------------------------
5) ls
[options] [directory or file] list directory contents or file permissions
At any
time you can determine where you are in the file system hierarchy with the pwd,
print workingdirectory, command.
------------------------------------------------------------------------------------------------------------------------------------------
6) mkdir
[options] --directory make a directory
You
extend your home hierarchy by making sub-directories underneath it. This is done
with the mkdir command. Again, you specify either the full or relative path of
the directory:
Syntax
mkdir
[options] directory
------------------------------------------------------------------------------------------------------------------------------------------
7) pwd
---- print working (current) directory
To find
out your current location—that is the directory in which you are currently
working
------------------------------------------------------------------------------------------------------------------------------------------
8) rmdir
[options] directory -------remove a directory
A
directory needs to be empty before you can remove it. If it’s not, you need to
remove the files first.Also, you can’t remove a directory if it is your present
working directory; you must first change outof it.
Syntax
rmdir
directory
------------------------------------------------------------------------------------------------------------------------------------------
9) ls
------list
The
command to list your directories and files is ls. With options it can provide
information about the size, type of file, permissions, dates of file creation,
change and access.
-a lists
all files, including those beginning with a dot (.)---hidden files
-d lists
only names of directories, not the files in the directory
-g
displays Unix group assigned to the file, requires the -l option (BSD only)
-l long
listing: lists the mode, link information, owner, size, last modification
(time). If the file is a symbolic link, an arrow (-->) precedes the pathname
-c list
in columns
-s to
ascertain the size of the file,The size indicated is the number of kilobytes,
rounded upward, for each file
-F Adding
the -F flag to ls appends suffixes to certain filenames so that you can
ascertain more easily what types of files they are.
-m This
flag outputs the files as a comma-separated list
File
syntax :
if file
ends with / ---directory
* ---executable prog
@---is a symbolic link to another file or directory
staying
in the same directory and searching the file :
ls -F
\tibco
ls -F ..
------------------------------------------------------------------------------------------------------------------------------------------
10) chgrp
[options] group file change the group of the file
------------------------------------------------------------------------------------------------------------------------------------------
11) chown
[options] owner file change the ownership of a file; can only be done by the
superuser
------------------------------------------------------------------------------------------------------------------------------------------
12) Rmdir
-remove any directory for which you have appropriate permissions
--To remove
a directory, you must first remove all files therein using the rm command.
--There’s
no way to restore a directory you’ve removed
--The
rmdir command removes only directories that are empty
------------------------------------------------------------------------------------------------------------------------------------------
13) cp
[options] file1 file2
copy
file1 into file2; file2 shouldn't already exist. This command creates or
overwrites file2.
The
format of a cp command is to specify first the name of the file you want to
copy and then the new filename. Both names must be either relative filenames or
absolute filenames.
--Copy
the contents of one file to another with the cp command.
--Cant
copy directories
--Can
copy many files at once if you specify a directory as the destination rather
than specifying a new filename.
Syntax
cp
[options] old_filename new_filename
Common
Options
-i
interactive (prompt and wait for confirmation before proceeding)
-r
recursively copy a directory
------------------------------------------------------------------------------------------------------------------------------------------
14) mv
[options] file1 file2
move
file1 into file2
--Rename
a file with the move command, mv.
--Rather
than creating multiple copies of the files you’re copying, mv physically
relocates them from the old directory to the new.
Syntax
mv
[options] old_filename new_filename
Common
Options
-i
interactive (prompt and wait for confirmation before proceeding)
-f don’t
prompt, even when copying over an existing target file (overrides -i)
------------------------------------------------------------------------------------------------------------------------------------------
15) rm
[options] file remove (delete) a file or directory
(-r
recursively deletes the directory and its contents)
(-i
prompts before removing files)
--Remove
a file with the rm, remove, command.
--The rm
command removes files permanently
--You can
remove more than one file at a time by specifying each of the files to the rm
command
Syntax
rm
[options] filename
Common
Options
-i
interactive (prompt and wait for confirmation before proceeding)
-r
recursively remove a directory, first removing the files and subdirectories
beneath it (but all files and directories inside it as well, to be removed.)
-f don’t
prompt for confirmation (overrides -i)
------------------------------------------------------------------------------------------------------------------------------------------
16) chmod
- change file permissions
The
command to change permissions on an item (file, directory, etc) is chmod
(change mode). The syntax involves using the command with three digits
(representing the user (owner, u) permissions,the group (g) permissions, and
other (o) user's permissions) followed by the argument (which may
be a file
name or list of files and directories). Or by using symbolic representation for
the permissions and who they apply to.
chmod
[who]op[perm] [argument list]
--- No
access is allowed
r--
Read-only access
r-x Read
and execute access, for programs and shell scripts
rw- Read
and write access, for files
rwx All
access allowed, for programs
Interpretation
of the following few examples should help:
-rw-------
1 taylor 3843 Oct 10 16:22 iecc.list
-rw-rw-r--
1 taylor 280232 Oct 10 16:22 mailing.lists
-rw-rw----
1 taylor 1031 Oct 7 15:44 newlists
-rwxr-x---
1 taylor 64 Oct 9 09:31 the.script
The first
file, iecc.list, has read and write permission for the owner (taylor) and is
off-limits
to all
other users. The file mailing.lists offers similar access to the file owner
(taylor) and
to the
group but offers read-only access to everyone else on the system. The third
file,
newlists,
provides read and write access to both the file owner and group, but no access
to
anyone
not in the group.
The
fourth file on the list, the.script, is a program that can be run by both the
owner and
group
members, read (or copied) by both the owner and group, and written (altered) by
the
owner. In
practice, this probably would be a shell script, as described earlier, and
these
permissions
would enable the owner (taylor) to use an editor to modify the commands
therein.
Other members of the group could read and use the shell script but would be
denied
access to
change it.
------------------------------------------------------------------------------------------------------------------------------------------
17) chown
- change ownership
Ownership
of a file can be changed with the chown command. On most versions of Unix this
can only be done by the super-user, i.e. a normal user can’t give away
ownership of their files. chown is used as below, where # represents the shell
prompt for the super-user:
Syntax
chown
[options] user[:group] file
------------------------------------------------------------------------------------------------------------------------------------------
18) cat
[options] file concatenate (list) a file
Display
the contents of a file with the concatenate command, cat.
Syntax
cat
[options] [file]
Common
Options
-n
precede each line with a line number
-v
display non-printing characters, except tabs, new-lines, and form-feeds
-e
display $ at the end of each line (prior to new-line) (when used with -v
option)
------------------------------------------------------------------------------------------------------------------------------------------
19) echo
[text string] echo the text string to stdout
The echo
command is used to repeat, or echo, the argument you give it back to the
standard output device. It normally ends with a line-feed, but you can specify
an option to prevent this.
Syntax
echo
[string]
------------------------------------------------------------------------------------------------------------------------------------------
20) head
[-number] file
--display
the first 10 (or number of) lines of a file
head
displays the head, or start, of the file.
head
[options] file
Common
Options
-n number
number of lines to display, counting from the top of the file
21) more
(or less or pg) [options] file page through a text file
------------------------------------------------------------------------------------------------------------------------------------------
22) tail
[options] file display the last few lines (or parts) of a file
tail
displays the tail, or end, of the file.
Syntax
tail
[options] file
Common
Options
-number
number of lines to display, counting from the bottom of the file
------------------------------------------------------------------------------------------------------------------------------------------
23) date
[options] report the current date and time
------------------------------------------------------------------------------------------------------------------------------------------
24) df
[options] [resource] report the summary of disk blocks and inodes free and in
use
df is
used to report the number of disk blocks and inodes used and free for each file
system. The
output
format and valid options are very specific to the OS and program version in
use.
Syntax
df
[options] [resource]
Common
Options
-l local
file systems only (SVR4)
-k report
in kilobytes (SVR4)
------------------------------------------------------------------------------------------------------------------------------------------
25) du
[options] [directory or file] report amount of disk space in use+
du
reports the amount of disk space in use for the files or directories you
specify.
Syntax
du [options]
[directory or file]
Common
Options
-a
display disk usage for each file, not just subdirectories
-s
display a summary total only
-k report
in kilobytes (SVR4)
------------------------------------------------------------------------------------------------------------------------------------------
26)
hostname/uname display or set (super-user only) the name of the current machine
------------------------------------------------------------------------------------------------------------------------------------------
27) kill
[options] [-SIGNAL] [pid#] [%job] send a signal to the process with the process
id number (pid#) or job
control
number (%n). The default signal is to kill the process.
kill
sends a signal to a process, usually to terminate it.
Syntax
kill
[-signal] process-id
------------------------------------------------------------------------------------------------------------------------------------------
28) man
[options] command show the manual (man) page for a command
------------------------------------------------------------------------------------------------------------------------------------------
29)
passwd [options] set or change your password
------------------------------------------------------------------------------------------------------------------------------------------
30) ps
[options] show status of active processes
ps is
used to report on processes currently running on the system. The output format
and valid
options
are very specific to the OS and program version in use.
Syntax
ps
[options]
------------------------------------------------------------------------------------------------------------------------------------------
31)
script file saves everything that appears on the screen to file until exit is
executed
script
creates a script of your session input and output. Using the script command,
you can capture
all the
data transmission from and to your terminal screen until you exit the script
program. This can
be useful
during the programming-and-debugging process, to document the combination of
things
you have
tried, or to get a printed copy of it all for later perusal.
Syntax
script
[-a] [file] <. . .> exit
------------------------------------------------------------------------------------------------------------------------------------------
32)
whereis [options] command report the binary, source, and man page locations for
the command
named
----------------------------------------------------------------------------------------------------------------------------------------------
33) which
command reports the path to the command or the shell alias in use
----------------------------------------------------------------------------------------------------------------------------------------------
34) who
or w report who is logged in and what processes are running
J10BCPNCAP
$ who
root
console Apr 26 10:17
tibadmin
pts/17 Jun 30 09:37
(10.8.149.62)
oracle
pts/18 Jun 27 14:24
(10.8.85.140)
tibadmin
pts/19 Jun 30 10:09 (10.8.149.154)
tibadmin
pts/21 Jun 30 15:11
(10.8.149.91)
tibadmin
pts/26 Jun 30 12:10
(10.8.74.107)
tibadmin
pts/27 Jun 30 12:55
(10.8.74.107)
----------------------------------------------------------------------------------------------------------------------------------------------
35) grep
The
grep utility is used to search for generalized regular expressions occurring in
Unix files.The egrep utility provides searching capability using an extended
set of meta-characters. The syntax of the grep utility, some of the available
options, and a few examples are
shown
below.
Syntax
grep
[options] regexp [file[s]]
Common
Options
-i ignore
case
-c report
only a count of the number of lines containing matches, not the
matches
themselves
-v invert
the search, displaying only lines that do not match
-n
display the line number along with the line on which a match was found
-s work
silently, reporting only the final status:
0, for
match(es) found
1, for no
matches
2, for
errors
-l list
filenames, but not lines, in which matches were found
----------------------------------------------------------------------------------------------------------------------------------------------
36)
whoami
J10BCPNCAP
$ whoami
tibadmin
----------------------------------------------------------------------------------------------------------------------------------------------
37) who
am i
J10BCPNCAP
$ who am i
tibadmin
pts/21 Jun 30 15:11
(10.8.149.91)
----------------------------------------------------------------------------------------------------------------------------------------------
38) id
The
purpose of
this
command is to tell you what group or groups you’re in and the numeric
identifier for your account name (known as your user ID number or user ID).
Enter id and see what you get. I get the following result:
% id
uid=211(taylor)
gid=50(users0) groups=50(users0)
%
J10BCPNCAP
$ id
uid=1005(tibadmin)
gid=1(other)
----------------------------------------------------------------------------------------------------------------------------------------------
39)
users-which lists the account names of all people using the system:
J10BCPNCAP
$ users
root
tibadmin oracle tibadmin tibadmin tibadmin tibadmin
----------------------------------------------------------------------------------------------------------------------------------------------
40) w
w
is a complex command which summarizes information
This is a
much more complex command, offering more information than either users or who.
Notice that the output is broken into different areas. The first line
summarizes the status of the system and, rather cryptically, the number of
programs that the computer is running at one time. Finally, for each user, the
output indicates the user name, the tty, when the user logged in to the system,
how long it’s been since the user has done anything (in minutes and seconds),
the combined CPU time of all jobs the user has run, and the amount of CPU time
taken by the
current
job. The last field tells you what you wanted to know in the first place: what
are the users doing?
3:18pm up 65 day(s), 11:12, 7 users, load average: 1.39,
1.42, 1.43
User
tty login@
idle JCPU PCPU what
root
console 26Apr1165days
-sh
tibadmin
pts/17 9:37am
5:40 1 1 tail
-100f SUBSCRIPTION_DTH-Proc
oracle
pts/18 Mon 2pm
3days
oracleSDP (DESCRIPTION=(LOCAL=YE
tibadmin
pts/19 10:09am
5:09 1 1 tail
-f SUBSCRIPTION_DTH-Process
tibadmin
pts/21
3:11pm
w
tibadmin
pts/26 12:10pm
3:07
-sh
tibadmin
pts/27 12:55pm
2:22
less ICCM_BW-ICCM_BW.log
----------------------------------------------------------------------------------------------------------------------------------------------
41) cal
shows a
simple calendar for the month or year specified.
eg:
$ cal
June 2011
S
M Tu W Th F S
1 2 3 4
5
6 7 8 9 10 11
12 13 14
15 16 17 18
19 20 21
22 23 24 25
26 27 28
29 30
For a
particular month cal [ [month] year ]
$ cal 3
1988
March 1988
S
M Tu W Th F S
1 2 3 4 5
6
7 8 9 10 11 12
13 14 15
16 17 18 19
20 21 22
23 24 25 26
27 28 29
30 31
cal 2007
2007
Jan
Feb
Mar
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1 2 3 4 5
6
1 2 3
1 2 3
7
8 9 10 11 12 13 4 5 6 7 8
9 10 4 5 6 7 8 9 10
14 15 16
17 18 19 20 11 12 13 14 15 16 17 11 12 13 14 15 16 17
21 22 23
24 25 26 27 18 19 20 21 22 23 24 18 19 20 21 22 23 24
28 29 30
31 25 26 27
28 25 26 27
28 29 30 31
Apr
May
Jun
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1
2 3 4 5 6
7 1 2 3
4
5
1 2
8
9 10 11 12 13 14 6 7 8 9 10 11
12 3 4 5 6 7 8 9
15 16 17
18 19 20 21 13 14 15 16 17 18 19 10 11 12 13 14 15 16
22 23 24
25 26 27 28 20 21 22 23 24 25 26 17 18 19 20 21 22 23
29
30
27 28 29 30 31 24 25 26 27 28
29 30
Jul
Aug
Sep
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1
2 3 4 5 6
7
1 2 3
4
1
8
9 10 11 12 13 14 5 6 7 8 9 10
11 2 3 4 5 6 7 8
15 16 17
18 19 20 21 12 13 14 15 16 17 18 9 10 11 12 13 14
15
22 23 24
25 26 27 28 19 20 21 22 23 24 25 16 17 18 19 20 21 22
29 30
31
26 27 28 29 30 31 23 24 25 26 27 28 29
30
Oct
Nov
Dec
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1 2 3 4 5
6
1 2
3
1
7
8 9 10 11 12 13 4 5 6 7 8
9 10 2 3 4 5 6 7 8
14 15 16 17
18 19 20 11 12 13 14 15 16 17 9 10 11 12 13 14 15
21 22 23
24 25 26 27 18 19 20 21 22 23 24 16 17 18 19 20 21 22
28 29 30
31 25 26 27
28 29 30 23 24 25 26 27 28 29
30 31
----------------------------------------------------------------------------------------------------------------------------------------------
42) bc
The bc
utility implements an arbitrary precision calculator.It takes
input from any files given, then reads from the standard input.
J10BCPNCAP
$ bc
4*2
8
5-8
-3
6+9
15
sqrt(25)
5
----------------------------------------------------------------------------------------------------------------------------------------------
43) dc
The dc
command works with the postfix notation, and each number or operation must be
on its own line. Further, the result of an operation isn’t
automatically
shown; you have to enter p to see the most recently calculated result.
J10BCPNCAP
$ dc
9
9
*
p
81
----------------------------------------------------------------------------------------------------------------------------------------------
44)
Directories
Any
filename that ends with a slash (/) is a folder (UNIX calls these directories).
Any filename that ends with an asterisk (*) is a program. Anything ending with
an at sign (@) is a symbolic link, and everything else is a normal, plain
file.directory .A type of UNIX file used to group other files. Files and
directories can be placed inside other directories, to build a hierarchical
system.
a) The
bin Directory
This
directory is used to store all the executable programs on the system.
b) The
dev Directory
All
device drivers—often numbering into the hundreds—are stored as separate files
in the standard UNIX dev (devices) directory.
c) The
etc Directory
The file
system, security, device drivers, hardware configurations, and more. It
designates the etc directory as the storage place for all administrative files
and information
d) The
lib Directory
UNIX has
a central storage place for function and procedural libraries. These specific
executables are included with specific programs, allowing
programs
to offer features and capabilities otherwise unavailable.
e) The
lost+found Directory
When
files are recovered after any sort of problem or failure, they are placed here,
in the lost+found directory, if the kernel cannot ascertain the proper location
in the file system.
f) The
mnt and sys Directories
The mnt
directory is intended to be a common place to mount external media—hard disks,
removable cartridge drives.
g) The
tmp Directory
If you’re
editing a file, for example, the program makes a copy of the file and saves it
in tmp, and you work directly with that, saving the new file back to your
original file only when you’ve completed your work.
h) The
usr Directory
This
directory was intended to be the central storage place for all user-related
commands.
i) Home
directory
This is
your private directory, and is also where you start out when you log in to the
system.
j) Root
directory
The
directory at the very top of the file system hierarchy, also known as slash.
----------------------------------------------------------------------------------------------------------------------------------------------
45)
Absolute and relative file names
If it’s a
slash, you’ve got an absolute filename (because the filename is rooted to the
very top level of the file system). If you don’t have a slash as the first
character, the filename’s a relative filename.
A hidden
file is any file with a dot as the first character of the filename.
. current
directory
.. parent
directory
Absolute
name :Specifying the location of a file in a hierarchy to ensure that the
filename is unique is known in UNIX parlance as specifying its absolute
filename. That is, regardless of where you are within the file system, the
absolute filename always specifies a particular file. By contrast, relative
filenames are not unique descriptors.
Relative
name :Relative filenames describe files that are referenced relative to an
assumed position in the file system.
----------------------------------------------------------------------------------------------------------------------------------------------
46) env
The env
utility obtains the current environment, modifies it according to
its arguments, then invokes the utility named by the utility operand with the
modified environment.
Environment
variables--
PATH-The
PATH environment variable lists the set of directories, in left-to-right order,
that the system searches to find commands and applications you request.
echo
$PATH
HOME-Your
home directory (as it’s known) is the name of the directory that you always
begin your UNIX session within.
echo
$HOME
----------------------------------------------------------------------------------------------------------------------------------------------
47)
dynamic linking Although most UNIX systems require all necessary utilities and
library
routines
(such as the routines for reading information from the keyboard and displaying
it
to the
screen) to be plugged into a program when it’s built (known in UNIX parlance as
static
linking),
some of the more sophisticated systems can delay this inclusion until you
actually
need to
run the program. In this case, the utilities and libraries are linked when you
start the
program,
and this is called dynamic linking.
----------------------------------------------------------------------------------------------------------------------------------------------
48)
symbolic link A file that contains a pointer to another file rather than
contents of its own.
This can
also be a directory that points to another directory rather than having files
of its own.
A useful
way to have multiple names for a single program or allow multiple people to
share
a single
copy of a file.
----------------------------------------------------------------------------------------------------------------------------------------------
49) touch
The touch
utility sets the access and modification times of each file.
The file operand is created if it does not
already exist.
----------------------------------------------------------------------------------------------------------------------------------------------
50)
Compress
The
compress program is given a list of filenames and then compresses each of the
files, renaming them with a .Z suffix, which indicates that
they are
compressed.
To
reverse the operation, use the companion command uncompress, and specify either
the current name of the file (that is, with the .Z suffix) or the name of the
file before it was compressed (that is, without the .Z suffix.
----------------------------------------------------------------------------------------------------------------------------------------------
51) file
--similar
to ls
J10BCPNCAP
$ file SUBSCRIPTION_DTH-Process_Archive.log
SUBSCRIPTION_DTH-Process_Archive.log:
ascii text
----------------------------------------------------------------------------------------------------------------------------------------------
52)
banner
banner
prints its arguments (each up to 10 characters long) in large letters on
the standard output.
Print
characters as a poster on the standard output. Each word supplied must contain
ten characters or less.
Eg : banner
archana
----------------------------------------------------------------------------------------------------------------------------------------------
53)
finger
Display
information about local and remote users.
----------------------------------------------------------------------------------------------------------------------------------------------
54) File
Redirection
File
redirection Most UNIX programs expect to read their input from the user (that
is, standard input) and write their output to the screen (standard output). By
use of file redirection, however, input can come from a previously created
file, and output can be saved to a file instead of being displayed on the
screen.
By
placing a file-redirection command in a regular command line:
< redirects
input,
>
redirects output
>>
redirects output and appends the information to the existing file.
cat <
file1 >file2
Copies
from file 1 to file2
cat >
new_filename
creates
new file
----------------------------------------------------------------------------------------------------------------------------------------------
55) WC
It
computes a word count for the file.
-w counts
words
-c
counts characters
-l
counts
----------------------------------------------------------------------------------------------------------------------------------------------
56) uniq
Sometimes
when you’re looking at a file, you’ll notice that there are many duplicate
entries, either blank lines or, perhaps, lines of repeated information. To
clean up these files and shrink their size at the same time, you can use the
uniq command, which lists each unique line in the file.
Well, it
sort of lists each unique line in the file. What uniq really does is compare
each line it reads with the previous line. If the lines are the same, uniq does
not list the second line. You can use flags with uniq to get more specific
results: -u lists only lines that are not repeated.
The uniq
command removes duplicate lines only if they’re adjacent.
-d lists
only lines that are repeated (the exact opposite of -u),
-c adds a
count of how many times each line occurred.
----------------------------------------------------------------------------------------------------------------------------------------------
57)
Standard input and output
When a
program is run, the default location for receiving input is called standard
input. The default location for output is standard output. If you are running
UNIX from a terminal, standard input and output are your terminal.
Standard
input UNIX programs always default to reading information from the user by
reading the keyboard and watching what’s typed. With file redirection, input
can come from a file, and with pipelines, input can be the result of a previous
UNIX command.
standard
error.
Standard
output, but you can redirect standard error to a different location than
standard output.
Standard
output When processing information, UNIX programs default to displaying the
output on the screen itself, also known as standard output. With file
redirection, output can easily be saved to a file; with pipelines, output can
be sent to other programs.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
58)Sort
A program
that reads information and sorts it alphabetically. The program sort also
enables you to sort lists of numbers.
To sort
filenames alphabetically regardless of case, you can use sort -f:
% ls -1 |
sort -f
To sort
lines of a file:
% sort
< testme
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
59)Number
Lines in Files Using cat -n and nl
To have a
line number listed next to each line of a file. It’s quite simple to do with
the cat program by specifying the -n flag to number lines in the file
displayed.A program that prefaces each line with a line number isn’t much of an
addition to the UNIX command toolbox.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
60) diff
compare
two files
The diff
utility will compare the contents of file1 and
file2 and write to standard output a list of changes necessary to
convert file1 into file2.
Eg : diff
mon.logins tues.logins
2d1
<
bsmith
4a4
> jdoe
7c7
<
mschmidt
---
> proy
Note that
the output lists the differences as well as in which file the difference
exists. Lines in the
first
file are preceded by "< ", and those in the second file are
preceded by "> ".
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
61) comm
select or
reject lines common to two files
The comm
utility reads file1 and file2, which
must be ordered in the current collating sequence,
and produces three text columns as output: lines only in
file1; lines only in file2; and lines in both files.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
62) nl
line
numbering
The best
option, though, is that nl can selectively number just those lines that contain
a specified pattern.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
63) spell
The
spell command collects words from the named files and
looks them up in a spelling list. Words that neither occur
among
nor are derivable (by applying certain inflections,
prefixes, or suffixes) from words in the spelling list are written
to the standard output.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
64)Filters
Filters
are a particular type of UNIX program that expects to work either with file
redirection or as part of a pipeline. These programs read input from standard
input, write output to standard output, and often don’t have any starting
arguments.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
65) Wild
Cards
There are
two wildcards to learn here: * acts as a match for any number and sequence of
characters, and ? acts as a match for any single character. In the broadest
sense, a lone * acts as a match for all files in the current directory (in
other words, ls * is identical to ls), whereas a single ? acts as a match for
all one-character-long filenames in a directory (for instance, ls?, which will
list only those filenames that are one character long).
Eg :
1) ls -ld
S*
2) ls -ld
S
3)ls -ld
a* b* k* o* s* t*
4)ls -ld
[abkost]*
5)ls -ld
[a-z]*
6)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
66) egrep
Sometimes
a single regular expression can’t locate what you seek. For example, perhaps
you’re looking for lines that have either one pattern or a second pattern.
That’s where the egrep command proves helpful. The command gets its name
from“expression grep,” and it has a notational scheme more powerful than that
of grep.( use the full set of alphanumeric and special
characters) to match the patterns)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
67) fgrep
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
68)
Expressions
Some text
processing programs, such as grep, egrep, sed, awk and vi, let you search on
patterns instead of fixed strings. These text patterns are known as regular
expressions. You form a regular expression by combining normal characters and
special characters, also known as meta-characters,
with the
rules below. With these regular expressions you can do pattern matching on text
data.
Regular
expressions come in three different forms:
• Anchors
which tie the pattern to a location on the line
•
Character sets which match a character at a single position
•
Modifiers which specify how many times to repeat the previous expression
1) .
match any single character except <newline>
2) *
match zero or more instances of the single character (or meta-character) immediately
preceding it
3) [abc]
match any of the characters enclosed
4) [a-d]
match any character in the enclosed range
5) [^exp]
match any character not in the following expression
6) ^abc
the regular expression must start at the beginning of the line (Anchor)
7) abc$
the regular expression must end at the end of the line (Anchor)
8) \
treat the next character literally. This is normally used to escape the meaning
of special characters such as "." and "*".
Example
1) To
find lines which begin with 'O'
grep ^O
time.sh
2) To
find lines which begin with 'SMS'
grep ^SMS
time.sh
3) To
find lines which begin with OMS
grep OMS*
time.sh
4) search
for any instances of t followed by zero or more occurrences of e
grep
'te*' num.list
5) search
for any instances of t followed by one or more occurrences of e
grep
'tee*' time.sh
6)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
69) sed -
stream editor
The
non-interactive, stream editor, sed, edits the input stream, line by line,
making the specified changes, and sends the result to standard output.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
70) AWK
awk is a
pattern scanning and processing language. Its name comes from the last initials
of the threeauthors: Alfred. V. Aho, Brian. W. Kernighan, and Peter. J.
Weinberger.
nawk is
new awk, a newer version of the program
gawk is
gnu awk, from the Free Software Foundation.
awk
searches its input for patterns and performs the specified operation on each
line, or fields of the line, that contain those patterns. You can specify the
pattern matching statements for awk either on the command line, or by putting
them in a file and using the -f program_file option.Each input line is checked
for a pattern match with the indicated action being taken on a match. This
continues through the full sequence of patterns, then the next line of input is
checked.
Input is
divided into records and fields.
Syntax
awk
program [file]
where
program is composed of one or more:
pattern {
action }
fields.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
71)cmp
[options] file1 file2
compare
two files and list where differences occur (text or binary files)
Eg : %
cmp mon.logins tues.logins
mon.logins
tues.logins differ: char 9, line 2
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
72) cut
[options] [file(s)]
The cut
command allows a portion of a file to be extracted for another use.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
73) find
find
files matching a type or pattern
The find
command will recursively search the indicated directory tree to find files
matching a type or pattern you specify. find can then list the files or execute
arbitrary commands based on the results.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
74) paste
- merge files
The paste
command allows two files to be combined side-by-side. The default delimiter
between the
columns
in a paste is a tab, but options allow other delimiters to be used.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
75) sort
[options] file sort the lines of the file according to the options chosen
The sort
command is used to order the lines of a file. Various options can be used to
choose the order
as well
as the field on which a file is sorted. Without any options, the sort compares
entire lines in the
file and
outputs them in ASCII order (numbers first, upper case letters, then lower case
letters).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
76) ln
The ln
command creates a "link" or an additional way to access (or gives an
additional name to)
another
file.
Syntax
ln
[options] source [target]
If not
specified target defaults to a file of the same name in the present working
directory.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
77) tee
tee sends
standard in to specified files and also to standard out. It’s often used in
command pipelines.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
78)
strings
To search
a binary file for printable, ASCII, strings use the strings command. It
searches for any sequence of 4 or more ASCII characters terminated
by
a <newline> or null character. I find this command useful for
searching for file names and possible error messages within compiled programs
that I
don’t have source code for.
Syntax
strings
[options] file
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
79) tr
The tr
command translates characters from stdin to stdout. With no options the
characters in string1 are translated into the characters in string2, character
by character in the string arrays. The first character in string1 is translated
into the first character in string2, etc.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
80) File
Compression
The
compress command is used to reduce the amount of disk space utilized by a file.
When a file has been compressed using the compress
command,
a suffix of .Z is appended to the file name. The ownership modes and access and
modification times of the original file are preserved. uncompress restores the
files originally compressed by compress.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
81) tar -
archive files
The tar
command combines files into one device or filename for archiving purposes. The
tar
command
does not compress the files; it merely makes a large quantity of files more
manageable
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
82)
uuencode/uudecode - encode a file
To encode
a binary file into 7-bit ASCII use the uuencode command. To decode the file
back to binary use the uudecode command. The uu in the names comes because they
are part of the
Unix-to-Unix
CoPy (UUCP) set of commands. The uuencode and uudecode commands are
commonly
used when sending binary files through e-mail. In e-mail there’s no guarantee
that 8-bit
binary
files will be transferred cleanly. So to ensure delivery you should encode the
binary file, either
directly,
on the command line and then include the encoded file, or indirectly, by
letting your MIME
mailer
program do it for you. In a similar manner, the user decodes the file on the
receiving end.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
83) od -
octal dump of a file
od dumps
a file to stdout in different formats, including octal, decimal, floating
point, hex, and
character
format.
Syntax
od
[options] file
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
84)
TELNET and FTP - remote login and file transfer protocols
TELNET
and FTP are Application Level Internet protocols. The TELNET and FTP protocol
specifications
have been implemented by many different sources, including The National Center
for
Supercomputer
Applications (NCSA), and many other public domain and shareware sources.
The
programs implementing the TELNET protocol are usually called telnet, but not
always. Some
notable
exceptions are tn3270, WinQVT, and QWS3270, which are also TELNET protocol
implementations.
TELNET is used for remote login to other computers on the Internet.
The
programs implementing the FTP protocol are usually called ftp, but there are
exceptions to that
too. A
program called Fetch, distributed by Dartmouth College, WS_FTP, written and
distributed by
John
Junod, and Ftptool, written by a Mike Sullivan, are FTP protocol
implementations with graphic
user
interfaces. There’s an enhanced FTP version, ncftp, that allows additional
features, written by
Mike
Gleason. Also, FTP protocol implementations are often included in TELNET
implementation
programs,
such as the ones distributed by NCSA. FTP is used for transferring files
between
computers
on the Internet.
rlogin is
a remote login service that was at one time exclusive to Berkeley 4.3 BSD UNIX.
Essentially,
it offers the same functionality as telnet, except that it passes to the remote
computer
information
about the user's login environment. Machines can be configured to allow
connections
from
trusted hosts without prompting for the users’ passwords. A more secure version
of this
protocol
is the Secure SHell, SSH, software written by Tatu Ylonen and available via
ftp://ftp.net.ohio-state.edu/pub/security/ssh.
From a
Unix prompt, these programs are invoked by typing the command (program name)
and the
(Internet)
name of the remote machine to which to connect. You can also specify various
options, as
allowed,
for these commands.
85)
Remote commands
A number
of Unix machines can be connected together to form a local area network. When
this is the
case, it
often happens that a user of one machine has valid login access to several of
the other
machines
in the local network. There are Unix commands available to such users which
provide
convenience
in carrying out certain common operations. Because these commands focus on
communications
with remote hosts in the local network, the command names begin with the letter
"r":
rlogin, rsh, and rcp. The remote access capability of these commands is
supported (optionally)
by the
dotfile, ~/.rhosts, for individual users and by the system-wide file
/etc/hosts.equiv. For
security
reasons these may be restricted on some hosts.
The
rlogin command allows remote login access to another host in the local network.
rlogin passes
information
about the local environment, including the value of the TERM environment
variable, to
the
remote host.
The rsh
command provides the ability to invoke a Unix shell on a remote host in the
local network for
the
purpose of executing a shell command there. This capability is similar to the
"shell escape"
function
commonly available from within such Unix software systems as editors and email.
The rcp
command provides the ability to copy files from the local host to a remote host
in the local
network.
Syntax
rlogin [
-l username ] remote_host
rsh [ -l
username ] remote_host [ command ]
rcp [
[user1]@host1:]original_filename [ [user2]@host2:]new_filename
where the
parts in brackets ([]) are optional. rcp does not prompt for passwords, so you
must have
permission
to execute remote commands on the specified machines as the selected user on
each
machine.
86)basename
deliver
portions of path names
basename
pathname [suffix]
Given a
pathname, strip the path prefix and leave just the filename, which is printed
on standard output. If specified, a filename suffix (e.g., .c) is removed also.
basename is typically invoked via command substitution (`...`) to generate a
filename. See also dirname.
The
Solaris version of basename allows the suffix to be a pattern of the form
accepted by expr. See the entry for expr for more detailsA command is a program
that tells the Unix system to do something. It has the form:
command
[options] [arguments]
An
argument indicates on what the command is to perform its action, usually a file
or series of files.
An option
modifies the command, changing the way it performs.
Commands
are case sensitive.
Options
are generally preceded by a hyphen (-), and for most commands, more than one
option can be strung together, in the form:
command
-[option][option][option]
Any
filename that ends with a slash (/) is a folder (UNIX calls these directories).
Any filename that ends with an asterisk (*) is a program. Anything ending with
an at sign (@) is a symbolic link, and everything else is a normal, plain file.
Advantages
of UNIX
multitasking
A multitasking computer is one that actually can run more than one
program,
or task, at a time. By contrast, most personal computers lock you into a single
program
that you must exit before you launch another.
multiuser
Computers intended to have more than a single person working on them
simultaneously
are designed to support multiple users, hence the term multiuser. By contrast,
personal
computers are almost always single-user because someone else can’t be running a
program
or editing a file while you are using the computer for your own work.
----------------------------------------------------------------------------------------------------------------------------------------------
1) ^D -
indicates end of data stream; can log a user off. The latter is disabled on
many systems
^C -
interrupt
^U
-Control-U is normally the "line-kill" signal for your terminal. When
typed it erases the entire input
logout -
leave the system
exit -
leave the shell
----------------------------------------------------------------------------------------------------------------------------------------------
2) id
id
- return user identity
You can
determine your userid and the list of groups you belong to with the id and
groups commands.
The
format in which we get as o/p is
"uid=%u(%s) gid=%u(%s)\n" <real user ID>, <user-name>,
<real group ID>, <group-name>
eg :
$ id
uid=1005(tibadmin)
gid=1(other)
$ id -a (
Reports user name, user ID and all the groups to which the
user belongs.)
uid=1005(tibadmin)
gid=1(other) groups=1(other)
----------------------------------------------------------------------------------------------------------------------------------------------
3) man
The Unix
manual, usually called man pages, is available on-line to explain the usage of
the Unix system and commands.
Syntax
man
[options] command_name
------------------------------------------------------------------------------------------------------------------------------------------------
4) cd
[directory] ---change directory
You can
change to a new directory with the cd command. cd will accept both absolute and
relative path names.
cd
-----changes to user's home directory
cd /
---changes directory to the system's root
cd ..
---goes up one directory level
cd ../..
--goes up two directory levels
cd
/full/path/name/from/root changes directory to absolute path named (note the
leading slash)
cd
path/from/current/location changes directory to path relative to current
location (no leading
slash)
cd
~--------username/directory changes directory to the named username's indicated
directory
----------------------------------------------------------------------------------------------------------------------------------------------
5) ls
[options] [directory or file] list directory contents or file permissions
At any
time you can determine where you are in the file system hierarchy with the pwd,
print workingdirectory, command.
----------------------------------------------------------------------------------------------------------------------------------------------
6) mkdir
[options] --directory make a directory
You
extend your home hierarchy by making sub-directories underneath it. This is
done with the mkdir command. Again, you specify either the full or relative
path of the directory:
Syntax
mkdir
[options] directory
----------------------------------------------------------------------------------------------------------------------------------------------
7) pwd
---- print working (current) directory
To find
out your current location—that is the directory in which you are currently
working
----------------------------------------------------------------------------------------------------------------------------------------------
8) rmdir
[options] directory -------remove a directory
A
directory needs to be empty before you can remove it. If it’s not, you need to
remove the files first.Also, you can’t remove a directory if it is your present
working directory; you must first change outof it.
Syntax
rmdir
directory
----------------------------------------------------------------------------------------------------------------------------------------------
9) ls
------list
The
command to list your directories and files is ls. With options it can provide
information about the size, type of file, permissions, dates of file creation,
change and access.
-a lists
all files, including those beginning with a dot (.)---hidden files
-d lists
only names of directories, not the files in the directory
-g
displays Unix group assigned to the file, requires the -l option (BSD only)
-l long
listing: lists the mode, link information, owner, size, last modification
(time). If the file is a symbolic link, an arrow (-->) precedes the pathname
-c list
in columns
-s to
ascertain the size of the file,The size indicated is the number of kilobytes,
rounded upward, for each file
-F Adding
the -F flag to ls appends suffixes to certain filenames so that you can
ascertain more easily what types of files they are.
-m This
flag outputs the files as a comma-separated list
File
syntax :
if file
ends with / ---directory
* ---executable prog
@---is a symbolic link to another file or directory
staying
in the same directory and searching the file :
ls -F \tibco
ls -F ..
----------------------------------------------------------------------------------------------------------------------------------------------
10) chgrp
[options] group file change the group of the file
----------------------------------------------------------------------------------------------------------------------------------------------
11) chown
[options] owner file change the ownership of a file; can only be done by the
superuser
----------------------------------------------------------------------------------------------------------------------------------------------
12) Rmdir
-remove any directory for which you have appropriate permissions
--To
remove a directory, you must first remove all files therein using the rm
command.
--There’s
no way to restore a directory you’ve removed
--The
rmdir command removes only directories that are empty
----------------------------------------------------------------------------------------------------------------------------------------------
13) cp
[options] file1 file2
copy
file1 into file2; file2 shouldn't already exist. This command creates or
overwrites file2.
The
format of a cp command is to specify first the name of the file you want to
copy and then the new filename. Both names must be either relative filenames or
absolute filenames.
--Copy
the contents of one file to another with the cp command.
--Cant
copy directories
--Can
copy many files at once if you specify a directory as the destination rather
than specifying a new filename.
Syntax
cp
[options] old_filename new_filename
Common
Options
-i
interactive (prompt and wait for confirmation before proceeding)
-r
recursively copy a directory
----------------------------------------------------------------------------------------------------------------------------------------------
14) mv
[options] file1 file2
move
file1 into file2
--Rename
a file with the move command, mv.
--Rather
than creating multiple copies of the files you’re copying, mv physically
relocates them from the old directory to the new.
Syntax
mv
[options] old_filename new_filename
Common
Options
-i
interactive (prompt and wait for confirmation before proceeding)
-f don’t
prompt, even when copying over an existing target file (overrides -i)
----------------------------------------------------------------------------------------------------------------------------------------------
15) rm
[options] file remove (delete) a file or directory
(-r
recursively deletes the directory and its contents)
(-i
prompts before removing files)
--Remove
a file with the rm, remove, command.
--The rm
command removes files permanently
--You can
remove more than one file at a time by specifying each of the files to the rm
command
Syntax
rm
[options] filename
Common
Options
-i
interactive (prompt and wait for confirmation before proceeding)
-r
recursively remove a directory, first removing the files and subdirectories
beneath it (but all files and directories inside it as well, to be removed.)
-f don’t
prompt for confirmation (overrides -i)
----------------------------------------------------------------------------------------------------------------------------------------------
16) chmod
- change file permissions
The
command to change permissions on an item (file, directory, etc) is chmod
(change mode). The syntax involves using the command with three digits
(representing the user (owner, u) permissions,the group (g) permissions, and
other (o) user's permissions) followed by the argument (which may
be a file
name or list of files and directories). Or by using symbolic representation for
the permissions and who they apply to.
chmod
[who]op[perm] [argument list]
--- No
access is allowed
r--
Read-only access
r-x Read
and execute access, for programs and shell scripts
rw- Read
and write access, for files
rwx All
access allowed, for programs
Interpretation
of the following few examples should help:
-rw-------
1 taylor 3843 Oct 10 16:22 iecc.list
-rw-rw-r--
1 taylor 280232 Oct 10 16:22 mailing.lists
-rw-rw----
1 taylor 1031 Oct 7 15:44 newlists
-rwxr-x---
1 taylor 64 Oct 9 09:31 the.script
The first
file, iecc.list, has read and write permission for the owner (taylor) and is
off-limits
to all
other users. The file mailing.lists offers similar access to the file owner
(taylor) and
to the
group but offers read-only access to everyone else on the system. The third
file,
newlists,
provides read and write access to both the file owner and group, but no access
to
anyone
not in the group.
The
fourth file on the list, the.script, is a program that can be run by both the
owner and
group
members, read (or copied) by both the owner and group, and written (altered) by
the
owner. In
practice, this probably would be a shell script, as described earlier, and
these
permissions
would enable the owner (taylor) to use an editor to modify the commands
therein.
Other members of the group could read and use the shell script but would be
denied
access to
change it.
----------------------------------------------------------------------------------------------------------------------------------------------
17) chown
- change ownership
Ownership
of a file can be changed with the chown command. On most versions of Unix this
can only be done by the super-user, i.e. a normal user can’t give away
ownership of their files. chown is used as below, where # represents the shell
prompt for the super-user:
Syntax
chown
[options] user[:group] file
----------------------------------------------------------------------------------------------------------------------------------------------
18) cat
[options] file concatenate (list) a file
Display
the contents of a file with the concatenate command, cat.
Syntax
cat
[options] [file]
Common
Options
-n
precede each line with a line number
-v
display non-printing characters, except tabs, new-lines, and form-feeds
-e
display $ at the end of each line (prior to new-line) (when used with -v
option)
----------------------------------------------------------------------------------------------------------------------------------------------
19) echo
[text string] echo the text string to stdout
The echo
command is used to repeat, or echo, the argument you give it back to the
standard output device. It normally ends with a line-feed, but you can specify
an option to prevent this.
Syntax
echo
[string]
----------------------------------------------------------------------------------------------------------------------------------------------
20) head
[-number] file
--display
the first 10 (or number of) lines of a file
head
displays the head, or start, of the file.
head
[options] file
Common
Options
-n number
number of lines to display, counting from the top of the file
----------------------------------------------------------------------------------------------------------------------------------------------
21) more
(or less or pg) [options] file page through a text file
----------------------------------------------------------------------------------------------------------------------------------------------
22) tail
[options] file display the last few lines (or parts) of a file
tail
displays the tail, or end, of the file.
Syntax
tail
[options] file
Common
Options
-number
number of lines to display, counting from the bottom of the file
----------------------------------------------------------------------------------------------------------------------------------------------
23) date
[options] report the current date and time
----------------------------------------------------------------------------------------------------------------------------------------------
24) df
[options] [resource] report the summary of disk blocks and inodes free and in
use
df is
used to report the number of disk blocks and inodes used and free for each file
system. The
output
format and valid options are very specific to the OS and program version in
use.
Syntax
df
[options] [resource]
Common
Options
-l local
file systems only (SVR4)
-k report
in kilobytes (SVR4)
----------------------------------------------------------------------------------------------------------------------------------------------
25) du
[options] [directory or file] report amount of disk space in use+
du
reports the amount of disk space in use for the files or directories you
specify.
Syntax
du
[options] [directory or file]
Common
Options
-a
display disk usage for each file, not just subdirectories
-s
display a summary total only
-k report
in kilobytes (SVR4)
----------------------------------------------------------------------------------------------------------------------------------------------
26)
hostname/uname display or set (super-user only) the name of the current machine
----------------------------------------------------------------------------------------------------------------------------------------------
27) kill
[options] [-SIGNAL] [pid#] [%job] send a signal to the process with the process
id number (pid#) or job
control
number (%n). The default signal is to kill the process.
kill
sends a signal to a process, usually to terminate it.
Syntax
kill
[-signal] process-id
----------------------------------------------------------------------------------------------------------------------------------------------
28) man
[options] command show the manual (man) page for a command
----------------------------------------------------------------------------------------------------------------------------------------------
29)
passwd [options] set or change your password
----------------------------------------------------------------------------------------------------------------------------------------------
30) ps
[options] show status of active processes
ps is
used to report on processes currently running on the system. The output format
and valid
options
are very specific to the OS and program version in use.
Syntax
ps
[options]
----------------------------------------------------------------------------------------------------------------------------------------------
31)
script file saves everything that appears on the screen to file until exit is
executed
script
creates a script of your session input and output. Using the script command,
you can capture
all the
data transmission from and to your terminal screen until you exit the script
program. This can
be useful
during the programming-and-debugging process, to document the combination of
things
you have
tried, or to get a printed copy of it all for later perusal.
Syntax
script
[-a] [file] <. . .> exit
----------------------------------------------------------------------------------------------------------------------------------------------
32)
whereis [options] command report the binary, source, and man page locations for
the command
named
----------------------------------------------------------------------------------------------------------------------------------------------
33) which
command reports the path to the command or the shell alias in use
----------------------------------------------------------------------------------------------------------------------------------------------
34) who
or w report who is logged in and what processes are running
J10BCPNCAP
$ who
root
console Apr 26 10:17
tibadmin
pts/17 Jun 30 09:37
(10.8.149.62)
oracle
pts/18 Jun 27 14:24
(10.8.85.140)
tibadmin
pts/19 Jun 30 10:09
(10.8.149.154)
tibadmin
pts/21 Jun 30 15:11
(10.8.149.91)
tibadmin
pts/26 Jun 30 12:10
(10.8.74.107)
tibadmin
pts/27 Jun 30 12:55
(10.8.74.107)
----------------------------------------------------------------------------------------------------------------------------------------------
35) grep
The
grep utility is used to search for generalized regular expressions occurring in
Unix files.The egrep utility provides searching capability using an extended
set of meta-characters. The syntax of the grep utility, some of the available
options, and a few examples are
shown below.
Syntax
grep
[options] regexp [file[s]]
Common
Options
-i ignore
case
-c report
only a count of the number of lines containing matches, not the
matches
themselves
-v invert
the search, displaying only lines that do not match
-n
display the line number along with the line on which a match was found
-s work
silently, reporting only the final status:
0, for
match(es) found
1, for no
matches
2, for
errors
-l list
filenames, but not lines, in which matches were found
----------------------------------------------------------------------------------------------------------------------------------------------
36)
whoami
J10BCPNCAP
$ whoami
tibadmin
----------------------------------------------------------------------------------------------------------------------------------------------
37) who
am i
J10BCPNCAP
$ who am i
tibadmin
pts/21 Jun 30 15:11
(10.8.149.91)
----------------------------------------------------------------------------------------------------------------------------------------------
38) id
The
purpose of
this
command is to tell you what group or groups you’re in and the numeric
identifier for your account name (known as your user ID number or user ID).
Enter id and see what you get. I get the following result:
% id
uid=211(taylor)
gid=50(users0) groups=50(users0)
%
J10BCPNCAP
$ id
uid=1005(tibadmin)
gid=1(other)
----------------------------------------------------------------------------------------------------------------------------------------------
39)
users-which lists the account names of all people using the system:
J10BCPNCAP
$ users
root
tibadmin oracle tibadmin tibadmin tibadmin tibadmin
----------------------------------------------------------------------------------------------------------------------------------------------
40) w
w
is a complex command which summarizes information
This is a
much more complex command, offering more information than either users or who.
Notice that the output is broken into different areas. The first line
summarizes the status of the system and, rather cryptically, the number of
programs that the computer is running at one time. Finally, for each user, the
output indicates the user name, the tty, when the user logged in to the system,
how long it’s been since the user has done anything (in minutes and seconds),
the combined CPU time of all jobs the user has run, and the amount of CPU time
taken by the
current
job. The last field tells you what you wanted to know in the first place: what
are the users doing?
3:18pm up 65 day(s), 11:12, 7 users, load average: 1.39,
1.42, 1.43
User
tty login@
idle JCPU PCPU what
root
console 26Apr1165days
-sh
tibadmin
pts/17 9:37am
5:40 1 1 tail
-100f SUBSCRIPTION_DTH-Proc
oracle
pts/18 Mon 2pm
3days
oracleSDP (DESCRIPTION=(LOCAL=YE
tibadmin
pts/19 10:09am
5:09 1 1 tail
-f SUBSCRIPTION_DTH-Process
tibadmin
pts/21
3:11pm
w
tibadmin
pts/26 12:10pm
3:07
-sh
tibadmin
pts/27 12:55pm
2:22
less ICCM_BW-ICCM_BW.log
----------------------------------------------------------------------------------------------------------------------------------------------
41) cal
shows a
simple calendar for the month or year specified.
eg:
$ cal
June 2011
S
M Tu W Th F S
1 2 3 4
5
6 7 8 9 10 11
12 13 14
15 16 17 18
19 20 21
22 23 24 25
26 27 28
29 30
For a
particular month cal [ [month] year ]
$ cal 3
1988
March 1988
S
M Tu W Th F S
1 2 3 4 5
6
7 8 9 10 11 12
13 14 15
16 17 18 19
20 21 22
23 24 25 26
27 28 29
30 31
cal 2007
2007
Jan
Feb
Mar
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1 2 3 4 5
6
1 2
3
1 2 3
7
8 9 10 11 12 13 4 5 6 7 8
9 10 4 5 6 7 8 9 10
14 15 16
17 18 19 20 11 12 13 14 15 16 17 11 12 13 14 15 16 17
21 22 23
24 25 26 27 18 19 20 21 22 23 24 18 19 20 21 22 23 24
28 29 30
31 25 26 27
28 25 26 27
28 29 30 31
Apr
May
Jun
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1
2 3 4 5 6
7 1 2 3
4
5
1 2
8
9 10 11 12 13 14 6 7 8 9 10 11
12 3 4 5 6 7 8 9
15 16 17
18 19 20 21 13 14 15 16 17 18 19 10 11 12 13 14 15 16
22 23 24
25 26 27 28 20 21 22 23 24 25 26 17 18 19 20 21 22 23
29
30
27 28 29 30 31 24 25 26 27 28
29 30
Jul
Aug
Sep
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1
2 3 4 5 6
7
1 2 3
4
1
8
9 10 11 12 13 14 5 6 7 8 9 10
11 2 3 4 5 6 7 8
15 16 17
18 19 20 21 12 13 14 15 16 17 18 9 10 11 12 13 14
15
22 23 24
25 26 27 28 19 20 21 22 23 24 25 16 17 18 19 20 21 22
29 30
31
26 27 28 29 30 31 23 24 25 26 27 28 29
30
Oct
Nov
Dec
S
M Tu W Th F S S M Tu W Th
F S S M Tu W Th F S
1 2 3 4 5
6
1 2
3
1
7
8 9 10 11 12 13 4 5 6 7 8
9 10 2 3 4 5 6 7 8
14 15 16
17 18 19 20 11 12 13 14 15 16 17 9 10 11 12 13 14
15
21 22 23
24 25 26 27 18 19 20 21 22 23 24 16 17 18 19 20 21 22
28 29 30
31 25 26 27
28 29 30 23 24 25 26 27 28 29
30 31
----------------------------------------------------------------------------------------------------------------------------------------------
42) bc
The bc
utility implements an arbitrary precision calculator.It takes
input from any files given, then reads from the standard input.
J10BCPNCAP
$ bc
4*2
8
5-8
-3
6+9
15
sqrt(25)
5
----------------------------------------------------------------------------------------------------------------------------------------------
43) dc
The dc
command works with the postfix notation, and each number or operation must be
on its own line. Further, the result of an operation isn’t
automatically
shown; you have to enter p to see the most recently calculated result.
J10BCPNCAP
$ dc
9
9
*
p
81
----------------------------------------------------------------------------------------------------------------------------------------------
44)
Directories
Any
filename that ends with a slash (/) is a folder (UNIX calls these directories).
Any filename that ends with an asterisk (*) is a program. Anything ending with
an at sign (@) is a symbolic link, and everything else is a normal, plain
file.directory .A type of UNIX file used to group other files. Files and
directories can be placed inside other directories, to build a hierarchical
system.
a) The
bin Directory
This
directory is used to store all the executable programs on the system.
b) The
dev Directory
All
device drivers—often numbering into the hundreds—are stored as separate files
in the standard UNIX dev (devices) directory.
c) The
etc Directory
The file
system, security, device drivers, hardware configurations, and more. It
designates the etc directory as the storage place for all administrative files
and information
d) The
lib Directory
UNIX has
a central storage place for function and procedural libraries. These specific
executables are included with specific programs, allowing
programs
to offer features and capabilities otherwise unavailable.
e) The
lost+found Directory
When
files are recovered after any sort of problem or failure, they are placed here,
in the lost+found directory, if the kernel cannot ascertain the proper location
in the file system.
f) The
mnt and sys Directories
The mnt
directory is intended to be a common place to mount external media—hard disks,
removable cartridge drives.
g) The
tmp Directory
If you’re
editing a file, for example, the program makes a copy of the file and saves it
in tmp, and you work directly with that, saving the new file back to your
original file only when you’ve completed your work.
h) The
usr Directory
This
directory was intended to be the central storage place for all user-related
commands.
i) Home
directory
This is
your private directory, and is also where you start out when you log in to the
system.
j) Root
directory
The
directory at the very top of the file system hierarchy, also known as slash.
----------------------------------------------------------------------------------------------------------------------------------------------
45)
Absolute and relative file names
If it’s a
slash, you’ve got an absolute filename (because the filename is rooted to the
very top level of the file system). If you don’t have a slash as the first
character, the filename’s a relative filename.
A hidden
file is any file with a dot as the first character of the filename.
. current
directory
.. parent
directory
Absolute
name :Specifying the location of a file in a hierarchy to ensure that the
filename is unique is known in UNIX parlance as specifying its absolute
filename. That is, regardless of where you are within the file system, the
absolute filename always specifies a particular file. By contrast, relative
filenames are not unique descriptors.
Relative
name :Relative filenames describe files that are referenced relative to an
assumed position in the file system.
----------------------------------------------------------------------------------------------------------------------------------------------
46) env
The env
utility obtains the current environment, modifies it according to
its arguments, then invokes the utility named by the utility operand with the
modified environment.
Environment
variables--
PATH-The
PATH environment variable lists the set of directories, in left-to-right order,
that the system searches to find commands and applications you request.
echo
$PATH
HOME-Your
home directory (as it’s known) is the name of the directory that you always
begin your UNIX session within.
echo
$HOME
----------------------------------------------------------------------------------------------------------------------------------------------
47)
dynamic linking Although most UNIX systems require all necessary utilities and
library
routines
(such as the routines for reading information from the keyboard and displaying
it
to the
screen) to be plugged into a program when it’s built (known in UNIX parlance as
static
linking),
some of the more sophisticated systems can delay this inclusion until you
actually
need to
run the program. In this case, the utilities and libraries are linked when you
start the
program,
and this is called dynamic linking.
----------------------------------------------------------------------------------------------------------------------------------------------
48)
symbolic link A file that contains a pointer to another file rather than
contents of its own.
This can
also be a directory that points to another directory rather than having files
of its own.
A useful
way to have multiple names for a single program or allow multiple people to
share
a single
copy of a file.
----------------------------------------------------------------------------------------------------------------------------------------------
49) touch
The touch
utility sets the access and modification times of each file.
The file operand is created if it does not
already exist.
----------------------------------------------------------------------------------------------------------------------------------------------
50)
Compress
The
compress program is given a list of filenames and then compresses each of the
files, renaming them with a .Z suffix, which indicates that
they are
compressed.
To
reverse the operation, use the companion command uncompress, and specify either
the current name of the file (that is, with the .Z suffix) or the name of the
file before it was compressed (that is, without the .Z suffix.
----------------------------------------------------------------------------------------------------------------------------------------------
51) file
--similar
to ls
J10BCPNCAP
$ file SUBSCRIPTION_DTH-Process_Archive.log
SUBSCRIPTION_DTH-Process_Archive.log:
ascii text
----------------------------------------------------------------------------------------------------------------------------------------------
52)
banner
banner
prints its arguments (each up to 10 characters long) in large letters on
the standard output.
Print
characters as a poster on the standard output. Each word supplied must contain
ten characters or less.
Eg :
banner archana
----------------------------------------------------------------------------------------------------------------------------------------------
53)
finger
Display
information about local and remote users.
----------------------------------------------------------------------------------------------------------------------------------------------
54) File
Redirection
File
redirection Most UNIX programs expect to read their input from the user (that
is, standard input) and write their output to the screen (standard output). By
use of file redirection, however, input can come from a previously created
file, and output can be saved to a file instead of being displayed on the
screen.
By
placing a file-redirection command in a regular command line:
<
redirects input,
>
redirects output
>>
redirects output and appends the information to the existing file.
cat <
file1 >file2
Copies
from file 1 to file2
cat >
new_filename
creates
new file
----------------------------------------------------------------------------------------------------------------------------------------------
55) WC
It
computes a word count for the file.
-w counts
words
-c
counts characters
-l
counts
----------------------------------------------------------------------------------------------------------------------------------------------
56) uniq
Sometimes
when you’re looking at a file, you’ll notice that there are many duplicate
entries, either blank lines or, perhaps, lines of repeated information. To
clean up these files and shrink their size at the same time, you can use the
uniq command, which lists each unique line in the file.
Well, it
sort of lists each unique line in the file. What uniq really does is compare
each line it reads with the previous line. If the lines are the same, uniq does
not list the second line. You can use flags with uniq to get more specific
results: -u lists only lines that are not repeated.
The uniq
command removes duplicate lines only if they’re adjacent.
-d lists
only lines that are repeated (the exact opposite of -u),
-c adds a
count of how many times each line occurred.
----------------------------------------------------------------------------------------------------------------------------------------------
57)
Standard input and output
When a
program is run, the default location for receiving input is called standard
input. The default location for output is standard output. If you are running
UNIX from a terminal, standard input and output are your terminal.
Standard
input UNIX programs always default to reading information from the user by
reading the keyboard and watching what’s typed. With file redirection, input
can come from a file, and with pipelines, input can be the result of a previous
UNIX command.
standard
error.
Standard
output, but you can redirect standard error to a different location than
standard output.
Standard
output When processing information, UNIX programs default to displaying the
output on the screen itself, also known as standard output. With file
redirection, output can easily be saved to a file; with pipelines, output can
be sent to other programs.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
58)Sort
A program
that reads information and sorts it alphabetically. The program sort also
enables you to sort lists of numbers.
To sort
filenames alphabetically regardless of case, you can use sort -f:
% ls -1 |
sort -f
To sort
lines of a file:
% sort
< testme
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
59)Number
Lines in Files Using cat -n and nl
To have a
line number listed next to each line of a file. It’s quite simple to do with
the cat program by specifying the -n flag to number lines in the file displayed.A
program that prefaces each line with a line number isn’t much of an addition to
the UNIX command toolbox.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
60) diff
compare
two files
The diff
utility will compare the contents of file1 and
file2 and write to standard output a list of changes necessary to
convert file1 into file2.
Eg : diff
mon.logins tues.logins
2d1
< bsmith
4a4
> jdoe
7c7
<
mschmidt
---
> proy
Note that
the output lists the differences as well as in which file the difference
exists. Lines in the
first
file are preceded by "< ", and those in the second file are
preceded by "> ".
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
61) comm
select or
reject lines common to two files
The comm
utility reads file1 and file2, which must
be ordered in the current collating sequence, and
produces three text columns as output: lines only in
file1; lines only in file2; and lines in both files.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
62) nl
line
numbering
The best
option, though, is that nl can selectively number just those lines that contain
a specified pattern.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
63) spell
The
spell command collects words from the named files and
looks them up in a spelling list. Words that neither occur
among
nor are derivable (by applying certain inflections,
prefixes, or suffixes) from words in the spelling list are written
to the standard output.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
64)Filters
Filters
are a particular type of UNIX program that expects to work either with file
redirection or as part of a pipeline. These programs read input from standard
input, write output to standard output, and often don’t have any starting
arguments.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
65) Wild
Cards
There are
two wildcards to learn here: * acts as a match for any number and sequence of
characters, and ? acts as a match for any single character. In the broadest
sense, a lone * acts as a match for all files in the current directory (in
other words, ls * is identical to ls), whereas a single ? acts as a match for
all one-character-long filenames in a directory (for instance, ls?, which will
list only those filenames that are one character long).
Eg :
1) ls -ld
S*
2) ls -ld
S
3)ls -ld
a* b* k* o* s* t*
4)ls -ld
[abkost]*
5)ls -ld
[a-z]*
6)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
66) egrep
Sometimes
a single regular expression can’t locate what you seek. For example, perhaps
you’re looking for lines that have either one pattern or a second pattern.
That’s where the egrep command proves helpful. The command gets its name
from“expression grep,” and it has a notational scheme more powerful than that
of grep.( use the full set of alphanumeric and special
characters) to match the patterns)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
67) fgrep
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
68)
Expressions
Some text
processing programs, such as grep, egrep, sed, awk and vi, let you search on
patterns instead of fixed strings. These text patterns are known as regular
expressions. You form a regular expression by combining normal characters and
special characters, also known as meta-characters,
with the
rules below. With these regular expressions you can do pattern matching on text
data.
Regular
expressions come in three different forms:
• Anchors
which tie the pattern to a location on the line
•
Character sets which match a character at a single position
•
Modifiers which specify how many times to repeat the previous expression
1) .
match any single character except <newline>
2) *
match zero or more instances of the single character (or meta-character)
immediately preceding it
3) [abc]
match any of the characters enclosed
4) [a-d]
match any character in the enclosed range
5) [^exp]
match any character not in the following expression
6) ^abc
the regular expression must start at the beginning of the line (Anchor)
7) abc$
the regular expression must end at the end of the line (Anchor)
8) \
treat the next character literally. This is normally used to escape the meaning
of special characters such as "." and "*".
Example
1) To
find lines which begin with 'O'
grep ^O
time.sh
2) To
find lines which begin with 'SMS'
grep ^SMS
time.sh
3) To
find lines which begin with OMS
grep OMS*
time.sh
4) search
for any instances of t followed by zero or more occurrences of e
grep
'te*' num.list
5) search
for any instances of t followed by one or more occurrences of e
grep
'tee*' time.sh
6)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
69) sed -
stream editor
The
non-interactive, stream editor, sed, edits the input stream, line by line,
making the specified changes, and sends the result to standard output.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
70) AWK
awk is a
pattern scanning and processing language. Its name comes from the last initials
of the threeauthors: Alfred. V. Aho, Brian. W. Kernighan, and Peter. J.
Weinberger.
nawk is
new awk, a newer version of the program
gawk is
gnu awk, from the Free Software Foundation.
awk
searches its input for patterns and performs the specified operation on each
line, or fields of the line, that contain those patterns. You can specify the
pattern matching statements for awk either on the command line, or by putting
them in a file and using the -f program_file option.Each input line is checked
for a pattern match with the indicated action being taken on a match. This
continues through the full sequence of patterns, then the next line of input is
checked.
Input is
divided into records and fields.
Syntax
awk
program [file]
where
program is composed of one or more:
pattern {
action }
fields.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
71)cmp
[options] file1 file2
compare
two files and list where differences occur (text or binary files)
Eg : %
cmp mon.logins tues.logins
mon.logins
tues.logins differ: char 9, line 2
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
72) cut
[options] [file(s)]
The cut
command allows a portion of a file to be extracted for another use.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
73) find
find
files matching a type or pattern
The find
command will recursively search the indicated directory tree to find files
matching a type or pattern you specify. find can then list the files or execute
arbitrary commands based on the results.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
74) paste
- merge files
The paste
command allows two files to be combined side-by-side. The default delimiter
between the
columns
in a paste is a tab, but options allow other delimiters to be used.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
75) sort
[options] file sort the lines of the file according to the options chosen
The sort
command is used to order the lines of a file. Various options can be used to
choose the order
as well
as the field on which a file is sorted. Without any options, the sort compares
entire lines in the
file and
outputs them in ASCII order (numbers first, upper case letters, then lower case
letters).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
76) ln
The ln
command creates a "link" or an additional way to access (or gives an
additional name to)
another
file.
Syntax
ln
[options] source [target]
If not
specified target defaults to a file of the same name in the present working
directory.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
77) tee
tee sends
standard in to specified files and also to standard out. It’s often used in
command pipelines.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
78)
strings
To search
a binary file for printable, ASCII, strings use the strings command. It
searches for any sequence of 4 or more ASCII characters terminated
by
a <newline> or null character. I find this command useful for
searching for file names and possible error messages within compiled programs
that I
don’t have source code for.
Syntax
strings
[options] file
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
79) tr
The tr
command translates characters from stdin to stdout. With no options the
characters in string1 are translated into the characters in string2, character
by character in the string arrays. The first character in string1 is translated
into the first character in string2, etc.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
80) File
Compression
The
compress command is used to reduce the amount of disk space utilized by a file.
When a file has been compressed using the compress
command,
a suffix of .Z is appended to the file name. The ownership modes and access and
modification times of the original file are preserved. uncompress restores the
files originally compressed by compress.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
81) tar -
archive files
The tar
command combines files into one device or filename for archiving purposes. The
tar
command
does not compress the files; it merely makes a large quantity of files more
manageable
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
82)
uuencode/uudecode - encode a file
To encode
a binary file into 7-bit ASCII use the uuencode command. To decode the file
back to binary use the uudecode command. The uu in the names comes because they
are part of the
Unix-to-Unix
CoPy (UUCP) set of commands. The uuencode and uudecode commands are
commonly
used when sending binary files through e-mail. In e-mail there’s no guarantee
that 8-bit
binary
files will be transferred cleanly. So to ensure delivery you should encode the
binary file, either
directly,
on the command line and then include the encoded file, or indirectly, by
letting your MIME
mailer
program do it for you. In a similar manner, the user decodes the file on the
receiving end.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
83) od -
octal dump of a file
od dumps
a file to stdout in different formats, including octal, decimal, floating
point, hex, and
character
format.
Syntax
od
[options] file
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
84)
TELNET and FTP - remote login and file transfer protocols
TELNET
and FTP are Application Level Internet protocols. The TELNET and FTP protocol
specifications
have been implemented by many different sources, including The National Center
for
Supercomputer
Applications (NCSA), and many other public domain and shareware sources.
The
programs implementing the TELNET protocol are usually called telnet, but not always.
Some
notable
exceptions are tn3270, WinQVT, and QWS3270, which are also TELNET protocol
implementations.
TELNET is used for remote login to other computers on the Internet.
The
programs implementing the FTP protocol are usually called ftp, but there are
exceptions to that
too. A
program called Fetch, distributed by Dartmouth College, WS_FTP, written and
distributed by
John
Junod, and Ftptool, written by a Mike Sullivan, are FTP protocol
implementations with graphic
user
interfaces. There’s an enhanced FTP version, ncftp, that allows additional
features, written by
Mike
Gleason. Also, FTP protocol implementations are often included in TELNET
implementation
programs,
such as the ones distributed by NCSA. FTP is used for transferring files
between
computers
on the Internet.
rlogin is
a remote login service that was at one time exclusive to Berkeley 4.3 BSD UNIX.
Essentially,
it offers the same functionality as telnet, except that it passes to the remote
computer
information
about the user's login environment. Machines can be configured to allow
connections
from
trusted hosts without prompting for the users’ passwords. A more secure version
of this
protocol
is the Secure SHell, SSH, software written by Tatu Ylonen and available via
ftp://ftp.net.ohio-state.edu/pub/security/ssh.
From a
Unix prompt, these programs are invoked by typing the command (program name)
and the
(Internet)
name of the remote machine to which to connect. You can also specify various
options, as
allowed,
for these commands.
85)
Remote commands
A number
of Unix machines can be connected together to form a local area network. When
this is the
case, it
often happens that a user of one machine has valid login access to several of
the other
machines
in the local network. There are Unix commands available to such users which
provide
convenience
in carrying out certain common operations. Because these commands focus on
communications
with remote hosts in the local network, the command names begin with the letter
"r":
rlogin, rsh, and rcp. The remote access capability of these commands is
supported (optionally)
by the
dotfile, ~/.rhosts, for individual users and by the system-wide file
/etc/hosts.equiv. For
security
reasons these may be restricted on some hosts.
The
rlogin command allows remote login access to another host in the local network.
rlogin passes
information
about the local environment, including the value of the TERM environment
variable, to
the
remote host.
The rsh
command provides the ability to invoke a Unix shell on a remote host in the
local network for
the
purpose of executing a shell command there. This capability is similar to the
"shell escape"
function
commonly available from within such Unix software systems as editors and email.
The rcp
command provides the ability to copy files from the local host to a remote host
in the local
network.
Syntax
rlogin [
-l username ] remote_host
rsh [ -l
username ] remote_host [ command ]
rcp [
[user1]@host1:]original_filename [ [user2]@host2:]new_filename
where the
parts in brackets ([]) are optional. rcp does not prompt for passwords, so you
must have
permission
to execute remote commands on the specified machines as the selected user on
each
machine.
86)basename
deliver
portions of path names
basename
pathname [suffix]
Given a
pathname, strip the path prefix and leave just the filename, which is printed
on standard output. If specified, a filename suffix (e.g., .c) is removed also.
basename is typically invoked via command substitution (`...`) to generate a
filename. See also dirname.
The
Solaris version of basename allows the suffix to be a pattern of the form
accepted by expr. See the entry for expr for more details
