#Bash 的 trap 命令

trap [OPTION]... [[CMD] SIGNAL_SPEC]

功能

捕获信号或 shell 退出事件，并执行指定命令。

类型

Bash 内置命令。

参数

OPTION 选项：
- -l - 打印信号名称及其对应编号的列表
- -p - 显示与每个 SIGNAL_SPEC 关联的陷阱命令
CMD - 要执行的命令；如果没有此参数，则清空所有关联的命令
SIGNAL_SPEC - 要捕获的信号或：
- EXIT - shell 退出时触发
- ERR - 任何命令返回非 0 时触发
- DEBUG - 每条命令执行前触发
- RETURN - 函数返回或 source 加载的脚本结束时触发

#示例

$ TEMP_FILE=$(mktemp)               # 创建临时文件
$ trap 'rm -f "$TEMP_FILE"' EXIT    # shell 退出时自动删除临时文件

#手册

trap: trap [-lp] [[arg] signal_spec ...]
    Trap signals and other events.

    Defines and activates handlers to be run when the shell receives signals
    or other conditions.

    ARG is a command to be read and executed when the shell receives the
    signal(s) SIGNAL_SPEC.  If ARG is absent (and a single SIGNAL_SPEC
    is supplied) or `-', each specified signal is reset to its original
    value.  If ARG is the null string each SIGNAL_SPEC is ignored by the
    shell and by the commands it invokes.

    If a SIGNAL_SPEC is EXIT (0) ARG is executed on exit from the shell.  If
    a SIGNAL_SPEC is DEBUG, ARG is executed before every simple command.  If
    a SIGNAL_SPEC is RETURN, ARG is executed each time a shell function or a
    script run by the . or source builtins finishes executing.  A SIGNAL_SPEC
    of ERR means to execute ARG each time a command's failure would cause the
    shell to exit when the -e option is enabled.

    If no arguments are supplied, trap prints the list of commands associated
    with each signal.

    Options:
      -l	print a list of signal names and their corresponding numbers
      -p	display the trap commands associated with each SIGNAL_SPEC

    Each SIGNAL_SPEC is either a signal name in <signal.h> or a signal number.
    Signal names are case insensitive and the SIG prefix is optional.  A
    signal may be sent to the shell with "kill -signal $$".

    Exit Status:
    Returns success unless a SIGSPEC is invalid or an invalid option is given.

#Bash 的 trap 命令

#示例

#手册

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