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71 lines
3.4 KiB
Markdown
71 lines
3.4 KiB
Markdown
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# The kill builtin command
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## Synopsis
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kill [-s SIGNAL | -n SIGNALNUMBER | -SIGNAL] PID|JOB
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kill -l|-L [SIGNAL...]
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## Description
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The `kill` command is used to send signals to processes specified by
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their `PID` or their `JOB`-specification.
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The signal(s) to be specified can have the following formats:
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- Numerical: The signal is specified using its constant numeric value.
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Be aware that not all systems have identical numbers for the signals.
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- Symbolic (long): The signal is specified using the same name that is
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used for the constant/macro in the C API (`SIG<name>`)
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- Symbolic (short): The signal is specified using the name from the C
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API without the `SIG`-prefix (`<name>`)
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Without any specified signal, the command sends the `SIGTERM`-signal.
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The `kill` command is a Bash builtin command instead of relying on the
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external `kill` command of the operating system to
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- be able to use shell job specifications instead of Unix process IDs
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- be able to send signals ("kill something") also, when your process
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limit is reached
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### Options
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| Option | Description |
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|:------------------|:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| `-s SIGNAL` | specifies the signal to send |
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| `-n SIGNALNUMBER` | specifies the signal to send |
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| `-SIGNAL` | specifies the signal to send |
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| `-l [SIGNAL...]` | Lists supported/known signal numbers and their symbolic name. If `SIGNAL` is given, only list this signal, translated (if a number is given the symbolic name is printed, and vice versa) |
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| `-L [SIGNAL...]` | Same as `-l [SIGNAL]` (compatiblity option) |
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### Return status
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| Status | Reason |
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|:-------|:----------------------------------------------------------------------------------------------------|
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| 0 | no error/success |
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| !=0 | invalid option |
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| !=0 | invalid signal specification |
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| !=0 | error returned by the system function (e.g. insufficient permissions to send to a specific process) |
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## Examples
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### List supported signals
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kill -l
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### Send KILL to a process ID
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kill -9 12345
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kill -KILL 12345
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kill -SIGKILL 12345
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## Portability considerations
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- POSIX(R) and ISO C only standardize symbolic signal names (no numbers)
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and a default action
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## See also
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