Question

我正在尝试在bash shell脚本中将grep用作变量和函数。当grep用作变量时，我得到所需的输出。将grep用作函数时，我没有得到想要的输出。

将grep用作变量的脚本如下：

#! /bin/bash

grep=$(grep -ico "mmshutdown: Finished" mmshutdown-output.txt)
#grep()
#{
#        grep -ico "mmshutdown: Finished" mmshutdown-output.txt
#}
status()
{
        echo $?
}

if [[ "grep" -gt "0" ]];
then
        echo
        echo "exit code of search  mmshutdown: Finished is $(status)"
        echo
        echo "FILE SYSTEM UNMOUNTED SUCESSFULLY"
        sleep 3
else
        echo "exit code of search mmshutdown: Finished is $(status)"
        echo "check output log file mmshutdown.txt"
        sleep 3
fi

运行脚本时的输出是

[root@ad ~]# ./grep-variable.sh

exit code of search  mmshutdown: Finished is 0

FILE SYSTEM UNMOUNTED SUCESSFULLY

函数中用于grep的脚本如下：

#! /bin/bash

#grep=$(grep -ico "mmshutdown: Finished" mmshutdown-output.txt)
grep()
{
        grep -ico "mmshutdown: Finished" mmshutdown-output.txt
}
status()
{
        echo $?
}


if [[ "grep" -gt "0" ]];
then
        echo
        echo "exit code of search  mmshutdown: Finished is $(status)"
        echo
        echo "FILE SYSTEM UNMOUNTED SUCESSFULLY"
        sleep 3
else
        echo "exit code of search mmshutdown: Finished is $(status)"
        echo "check output log file mmshutdown.txt"
        sleep 3
fi

运行脚本时的输出是

[root@ad ~]# ./grep-function.sh
exit code of search mmshutdown: Finished is 1
check output log file mmshutdown.txt

有人可以指出这里出了什么问题吗？为什么将grep用作函数不能提供所需的输出？

Answer 1

您的两个程序都将“ grep”与“ 0”进行比较，而不是grep命令的输出。另外-c选项返回匹配的行数。

检查以下与grep一起使用的代码。但是由于grep是一个函数，您将需要调用原始grep即具有完整路径的命令，否则它将陷入无限循环。将输出发送到/ dev / null并处理命令执行状态。

#! /bin/bash
set -x
#grep=$(grep -ico "mmshutdown: Finished" mmshutdown-output.txt)
grep()
{
        return $(/bin/grep -ico "mmshutdown: Finished" mmshutdown-output.txt > /dev/null)
}
status()
{
        echo $?
}


if  grep;
then
        echo
        echo "exit code of search  mmshutdown: Finished is $(status)"
        echo
        echo "FILE SYSTEM UNMOUNTED SUCESSFULLY"
        sleep 3
else
        echo "exit code of search mmshutdown: Finished is $(status)"
        echo "check output log file mmshutdown.txt"
        sleep 3
fi

为什么grep在linux shell脚本中用作变量时不起作用？

1 个答案: