linux - 无论 PID 结果如何，当从 ps 管道传输到 grep 时，Bash 脚本输出始终为 'ps'

Question

给定一个 pid 数组和代码:

    for i in ${listedPids[@]}
    do
        runningCheck="ps -u $USER | grep $i"
        grepRes=(${runningCheck})
        if [[ -n $grepRes ]]
        then
        echo $grepRes
        echo $runningCheck
            ... code not related to the issue
        fi
    done

无论这些 pid 是否处于事件状态；我一直从 echo $grepRes 获取“ps”，而 echo $runningCheck 的输出显示正确的用户名和 pid。我错过了什么？

Answer 1

替换

"ps -u $USER | grep $i"

通过

$(ps -u $USER | grep $i)

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Command Substitution: Bash performs the expansion by executing your command and replacing the command substitution with the standard output of the command, with any trailing newlines deleted.