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45 lines
1.7 KiB
Text
45 lines
1.7 KiB
Text
\section trap trap - perform an action when the shell receives a signal
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\subsection trap-synopsis Synopsis
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\fish{synopsis}
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trap [OPTIONS] [[ARG] SIGSPEC ... ]
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\endfish
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\subsection trap-description Description
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`trap` is a wrapper around the fish event delivery
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framework. It exists for backwards compatibility with POSIX
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shells. For other uses, it is recommended to define an <a
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href='index.html#event'>event handler</a>.
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The following parameters are available:
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- `ARG` is the command to be executed on signal delivery.
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- `SIGSPEC` is the name of the signal to trap.
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- `-h` or `--help` displays help and exits.
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- `-l` or `--list-signals` prints a list of signal names.
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- `-p` or `--print` prints all defined signal handlers.
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If `ARG` and `SIGSPEC` are both specified, `ARG` is the command to be
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executed when the signal specified by `SIGSPEC` is delivered.
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If `ARG` is absent (and there is a single SIGSPEC) or -, each specified
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signal is reset to its original disposition (the value it had upon
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entrance to the shell). If `ARG` is the null string the signal
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specified by each `SIGSPEC` is ignored by the shell and by the commands
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it invokes.
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If `ARG` is not present and `-p` has been supplied, then the trap commands
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associated with each `SIGSPEC` are displayed. If no arguments are
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supplied or if only `-p` is given, `trap` prints the list of commands
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associated with each signal.
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Signal names are case insensitive and the `SIG` prefix is optional.
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The return status is 1 if any `SIGSPEC` is invalid; otherwise trap
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returns 0.
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\subsection trap-example Example
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`trap "status --print-stack-trace" SIGUSR1` prints a stack trace
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each time the `SIGUSR1` signal is sent to the shell.
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