/bin/true

true命令啥都不作，只設置退出碼爲0。
在Linux底下，每一個程序執行完畢都會返回一個退出碼給調用者，通常狀況下0表示成功，其餘值代表有問題，固然某些程序的退出碼有特殊含義。有些shell下true多是個內建命令，至少bash下是。（do nothing, successfully。Exit with a status code indicating success. NOTE: your shell may have its own version of true, which usually supersedes the version described here. Please refer to your shell’s documentation for details about the options it supports.）
相對應的命令是false，也是啥都不幹，但退出碼設置爲1。