skill Command in Unix and Linux

skill Command in Unix and Linux

skill Command in Unix and Linux is used to send an signals to users and process. Using skill command we can halt a user terminal or can logout him. But keep in mind that you should be root to stop other users.

There is a package called procps It includes various useful (nifty) utilities. One of such utility is skill which is responsible to send a signal to users and process such as:

  •   Halt user terminal
  •   Kill user and logout

Usage:   skill [signal to send] [options] process selection criteria
Example: skill -KILL -v pts/*

1. To halt/stop a user called ravi

Send STOP signal to user ravi, type the following command:

[root@TechTutorial ~]# skill -STOP -u ravi

2. To resume already halted user called ravi

Send CONT signal to user ravi, type the following command:

[root@TechTutorial ~]# skill -CONT -u ravi

3. To kill and logout user called ravi

You can send KILL signal, type the following command:

[root@TechTutorial ~]# skill -KILL -u ravi

4. To kill and logout all users

type the following command:

Note: Do not run this command on any production boxes, this command just for demonstration purpose only.

[root@TechTutorial ~]# skill -KILL -v /dev/pts/*

PROCESS SELECTION OPTIONS

Selection criteria can be: terminal, user, pid, command. The options below may be used to ensure correct interpretation.
-t    The next argument is a terminal (tty or pty).
-u    The next argument is a username.
-p    The next argument is a process ID number.
-c    The next argument is a command name.

SIGNALS

The signals listed below may be available for use with skill. When known, numbers and default behavior are shown.

Name Num Action Description
0 0 n/a exit code indicates if a signal may be sent
ALRM 14 exit
HUP 1 exit
INT 2 exit
KILL 9 exit this signal may not be blocked
PIPE 13 exit
POLL exit
PROF exit
TERM 15 exit
USR1 exit
USR2 exit
VTALRM exit
STKFLT exit may not be implemented
PWR ignore may exit on some systems
WINCH ignore
CHLD ignore
URG ignore
TSTP stop may interact with the shell
TTIN stop may interact with the shell
TTOU stop may interact with the shell
STOP stop this signal may not be blocked
CONT restart continue if stopped, otherwise ignore
ABRT 6 core
FPE 8 core
ILL 4 core
QUIT 3 core
SEGV 11 core
TRAP 5 core
SYS core may not be implemented
EMT core may not be implemented
BUS core core dump may fail
XCPU core core dump may fail
XFSZ core core dump may fail

Lets see the Video of skill command in Unix and Linux

Do remember to comment your valuable feedback ….

Thanks for your wonderful Support and Encouragement

Ankam Ravi Kumar

Working as Linux / Storage Administrator L3. Interested in sharing the knowledge.

Leave a Reply

Your email address will not be published.