Linux的trap命令怎么使用

1. Linux信号

Linux系统利用信号与系统中的进程进行通信。Linux的常见信号有：

2. 信号组合键

Ctrl+C组合键会产生SIGINT信号，Ctrl+Z会产生SIGTSTP信号。

3. trap命令

trap命令允许你来指定shell脚本要监视并拦截的Linux信号。trap命令的格式为：trap commands signals。

demo1

shell脚本：

#!/bin/bash# test trap commandtrap "echo 'Sorry! I have trapped Ctrl-C'" SIGINTecho This is a test scriptcount=1while [ $count -le 10 ]do  echo "Loop $count"  sleep 1  count=$[ $count + 1 ]doneecho The end.

运行结果：

This is a test scriptLoop 1Loop 2^CSorry! I have trapped Ctrl-CLoop 3Loop 4^CSorry! I have trapped Ctrl-CLoop 5Loop 6Loop 7Loop 8^CSorry! I have trapped Ctrl-CLoop 9Loop 10The end.

demo2

除了在shell脚本中捕获信号外，也可以在shell退出时捕获，在trap命令后加上EXIT信号就行。

shell脚本：

#!/bin/bash# test trap commandtrap "echo Goodbye." EXITecho This is a test scriptcount=1while [ $count -le 10 ]do  echo "Loop $count"  sleep 1  count=$[ $count + 1 ]doneecho The end.

运行结果：

This is a test scriptLoop 1Loop 2Loop 3Loop 4Loop 5Loop 6Loop 7Loop 8Loop 9Loop 10The end.Goodbye.

demo3——修改trap操作

#!/bin/bash# test trap commandtrap "echo 'Sorry! I have trapped Ctrl-C'" SIGINTcount=1while [ $count -le 5 ]do  echo "Loop $count"  sleep 1  count=$[ $count + 1 ]donetrap "echo 'Sorry! The trap has been modified.'" SIGINTcount=1while [ $count -le 5 ]do  echo "Loop $count"  sleep 1  count=$[ $count + 1 ]doneecho The end.

运行结果：

Loop 1Loop 2Loop 3^CSorry! I have trapped Ctrl-CLoop 4Loop 5Loop 1Loop 2Loop 3^CSorry! The trap has been modified.Loop 4Loop 5The end.

demo4

删除捕获，命令形式为：trap -- ***，例如trap -- SIGINT