1) Command : man
Use : This command is
used for getting help about UNIX commands.
Syntax : man <command
name>
2) Command : grep
Use : This command
is used to search for a particular expression in the given input.
Syntax : grep
[OPTION]... PATTERN [FILE]...
e.g. : grep
<pattern> <file> ---> It can be used to search from
lines matching pattern from file.
grep -v
<pattern> <file> --> It can be used to search for
lines not matching pattern
from file.
3) Command : ps
Use : This command is
used to see the processes running on the system.
Syntax : ps [options]
e.g. : ps -ef --->
It can used to see the all processes from all users.
ps -ef |
grep <process_name> | grep -v grep ---> It can be used to
check whether a particular process is running or
not.
ps -fu <user_name>
---> It can be used to see all processes started by a particular
user.
4) Command : uptime
Use :This command is
used check the server/system run duration and number of users
currently logged on.
Syntax : uptime
e.g. : user@machine
:~$ uptime
17:16:31 up
7:34, 1 user, load average: 0.83, 0.87, 1.03
5) Command : whatis
Use : This command
displays manual page descriptions.
Syntax : whatis
<command_name>
e.g. : user@machine
:~$ whatis firefox
firefox (1)
- a free and open source web browser from Mozilla
6) Command : kill
Use : This command
send a signal ( default SIGTERM ) to a process.
Syntax : kill
<process_id>
e.g. : kill 123 543
2341 3453
---> Send the default signal, SIGTERM, to all those
processes.
7) Command : ls
Use : This command
is used to list directory contents.
Syntax : ls
[OPTION]... [FILE]...
e.g. : ls -l --->
It shows a log list of all files in the current directory.
8) Command : rm
Use : This command is
used to remove files or directories.
Syntax : rm
[OPTION]... [FILE]...
e.g. : rm <file_name>
---> It removes the <file_name> .
rm -r
<directory_name> --> It removes <directory_name> and
all the files/directory inside it.
9) Command : xargs
Use : This command
build and execute command lines from standard input.
Syntax :
<some_command> | xargs <another_command >
e.g. : ls
<file_name_pattern> | xargs rm ---> It is used to delete all
files as shown by output of ls
<file_name_pattern> .
