90 lines
2.6 KiB
Markdown
90 lines
2.6 KiB
Markdown
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# The `kill` command
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`kill` command in Linux (located in /bin/kill), is a built-in command which is used to terminate processes manually. The `kill` command sends a signal to a process which terminates the process. If the user doesn’t specify any signal which is to be sent along with kill command then default _TERM_ signal is sent that terminates the process.
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Signals can be specified in three ways:
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- **By number (e.g. -5)**
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- **With SIG prefix (e.g. -SIGkill)**
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- **Without SIG prefix (e.g. -kill)**
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### Syntax
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```
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kill [OPTIONS] [PID]...
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```
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### Examples:
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1. To display all the available signals you can use below command option:
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```
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kill -l
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```
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2. To show how to use a _PID_ with the _kill_ command.
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```
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$kill pid
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```
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3. To show how to send signal to processes.
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```
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kill {-signal | -s signal} pid
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```
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4. Specify Signal:
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- using numbers as signals
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```
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kill -9 pid
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```
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- using SIG prefix in signals
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```
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kill -SIGHUP pid
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```
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- without SIG prefix in signals
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```
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kill -HUP pid
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```
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### Arguments:
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The list of processes to be signaled can be a mixture of names and PIDs.
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pid Each pid can be expressed in one of the following ways:
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n where n is larger than 0. The process with PID n is signaled.
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0 All processes in the current process group are signaled.
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-1 All processes with a PID larger than 1 are signaled.
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-n where n is larger than 1. All processes in process group n are signaled.
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When an argument of the form '-n' is given, and it is meant to denote a
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process group, either a signal must be specified first, or the argument must
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be preceded by a '--' option, otherwise it will be taken as the signal to
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send.
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name All processes invoked using this name will be signaled.
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### Options:
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-s, --signal signal
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The signal to send. It may be given as a name or a number.
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-l, --list [number]
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Print a list of signal names, or convert the given signal number to a name. The
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signals can be found in /usr/include/linux/signal.h.
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-L, --table
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Similar to -l, but it will print signal names and their corresponding numbers.
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-a, --all
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Do not restrict the command-name-to-PID conversion to processes with the same UID
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as the present process.
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-p, --pid
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Only print the process ID (PID) of the named processes, do not send any signals.
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--verbose
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Print PID(s) that will be signaled with kill along with the signal.
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