功能: 在 Shell 中,使用 `trap` 命令来捕捉信号(事件)。

用法

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trap {命令} {信号数字列表}

信号数字 什么时候会出现
0 shell 关闭
1 挂起
2 终端 (CTRL+C)
3 退出
9 杀死 (无法被捕捉)

示例

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#
# signal is trapped to delete temporary file
#
del_file()
{
echo "* * * CTRL + C Trap Occurs (removing temporary file)* * *"
rm -f /tmp/input0.$$
exit 1
}
Take_input1()
{
recno=0
clear
echo "Appointment Note keeper Application for Linux"
echo -n "Enter your database file name : "
read filename
if [ ! -f $filename ]; then
echo "Sorry, $filename does not exit, Creating $filename database"
echo "Appointment Note keeper Application database file" > $filename
fi
echo "Data entry start data: `date`" >/tmp/input0.$$
#
# Set a infinite loop
#
while :
do
echo -n "Appointment Title:"
read na
echo -n "time :"
read ti
echo -n "Any Remark :"
read remark
echo -n "Is data okay (y/n) ?"
read ans
if [ $ans = y -o $ans = Y ]; then
recno=`expr $recno + 1`
echo "$recno. $na $ti $remark" >> /tmp/input0.$$
fi
echo -n "Add next appointment (y/n)?"
read isnext
if [ $isnext = n -o $isnext = N ]; then
cat /tmp/input0.$$ >> $filename
rm -f /tmp/input0.$$
return # terminate loop
fi
done # end_while
}
#
# Set trap to for CTRL+C interrupt i.e. Install our error handler
# When occurs it first it calls del_file() and then exit
#
trap del_file 2
#
# Call our user define function : Take_input1
#
Take_input1

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