前言

大家在工作的時(shí)候可能經(jīng)常會遇到這樣的需求，在類Unix系統(tǒng)的Bash環(huán)境下，怎樣檢查文件是否存在呢？既然有需求，當(dāng)然就有解決的辦法了，Shell中的test命令，可以用來檢測文件的類型或者比較數(shù)值是否相等，該命令也能用來檢查文件是否存在。

可以用如下的命令來進(jìn)行檢查：

test -e filename[ -e filename ] test -f filename[ -f filename ]

下面的命令，則使用Shell的條件表達(dá)式，判斷/etc/hosts文件是否存在：

[ -f /etc/hosts ] && echo "Found" || echo "Not found"

該組合命令會輸出以下內(nèi)容：

Found

更常見的用法，則是將test命令放置在if..else..fi條件判斷的條件表達(dá)式，然后在其中寫上不同的分支邏輯

#!/bin/bashfile="/etc/hosts"if [ -f "$file" ]then echo "$file found."else echo "$file not found."fi

檢測文件屬性的相關(guān)操作符

如果文件存在，并且具有相應(yīng)的屬性，如下的操作符都會返回true：

  -b FILE    FILE exists and is block special  -c FILE    FILE exists and is character special  -d FILE    FILE exists and is a directory  -e FILE    FILE exists  -f FILE    FILE exists and is a regular file  -g FILE    FILE exists and is set-group-ID  -G FILE    FILE exists and is owned by the effective group ID  -h FILE    FILE exists and is a symbolic link (same as -L)  -k FILE    FILE exists and has its sticky bit set  -L FILE    FILE exists and is a symbolic link (same as -h)  -O FILE    FILE exists and is owned by the effective user ID  -p FILE    FILE exists and is a named pipe  -r FILE    FILE exists and read permission is granted  -s FILE    FILE exists and has a size greater than zero  -S FILE    FILE exists and is a socket  -t FD file descriptor FD is opened on a terminal  -u FILE    FILE exists and its set-user-ID bit is set  -w FILE    FILE exists and write permission is granted  -x FILE    FILE exists and execute (or search) permission is granted

以上命令，從man test復(fù)制而來。

使用上述符號的方法一模一樣：

if [ operator FileName ]then  echo "FileName - Found, take some action here"else echo "FileName - Not found, take some action here"fi

總結(jié)

以上就是這篇文章的全部內(nèi)容了，希望本文的內(nèi)容對大家的學(xué)習(xí)或者工作能帶來一定的幫助，如果有疑問大家可留言交流。