====== Perl 呼叫外部程式命令差異 ======

==== system() : 呼叫後會回來繼續往下執行 ====
    * Exp1. <cli>system("/usr/local/share/ca-certificates/; sudo update-ca-certificates; sudo systemctl restart docker.service");</cli>
    * Exp2. <cli>system("sh", "script.sh", "--help" );</cli>
    * Exp3. <cli>system("sh script.sh --help");</cli>
==== exec() : 呼叫後就不會回來 ====
    * Exp1. <cli>exec("vi abc.txt");</cli> 
==== backticks(` `) 或是 qx/ / : 呼叫後會回來, 可將執行的結果傳入變數 ==== 
    * Exp1. $cmd_msg 內就是回傳執行的結果 <cli> $cmd_msg = `ls -l`;</cli>
    * Exp2. 搭配 2>&1 可讓所有訊息都導回來 <cli> $cmd_msg = `sudo apt update -y 2>&1`;</cli>
    * Exp3. 也可使用 qx/ / 語法<cli> $cmd_msg = qx/script.sh --option/;</cli>

===== 參考網址 =====
  * https://stackoverflow.com/questions/3200801/how-can-i-call-a-shell-command-in-my-perl-script

{{tag>perl}}