68.查看子進程腳本

思路： ps -elf查看進程ppid根據ppid賽選pid進程
#!/bin/bash
#The script is used to print child processes.
#Date 2021-01-16
file=/tmp/pid.txt #定義文本路徑
while :
do
read -p "please input a pid: " pid
if [ -z $pid ];then#判斷是否爲空
        echo "The input can not be empty (input q or quit to exit)."
        continue
elif [ $pid == "q" ]||[ $pid == "quit" ];then#退出循環
        echo "exit."
        exit
fi
ps -elf| awk -v pid2=$pid '$5==pid2 {print $0}'>$file#篩選pid
if ! grep -qw "$pid" $file;then#過濾pid
        echo "The input pid does not exist (input q or quit to exit)."
        continue
fi
break
done
child_pid() {
        ps -elf|awk -v pid_new=$1 '$5==pid_new {print $4}' >$1.txt
                #將進程id寫入文本
        n=`wc -l $1.txt| awk '{print $1}'`
        if [ $n -eq 0 ];then
        echo "There are no subprocess under the pid $1"
        elif [ $n -ne 0 ];then
        echo "The pid $1 subprocess according to following:"
                cat $1.txt
        fi
}#定義篩選函數
child_pid $pid

for i in `cat $pid.txt`
#for循環將每一個子進程包含的子進程篩選出
do
        child_pid $i
done
for i in `cat $pid.txt`
#for循環遍歷刪除文本
do
        [ -f $i.txt ] && rm $i.txt
done
[ -f $pid.txt ] && rm $pid.txt#刪除文本