前言
大家在工作的時候可能經(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操作符
如果文件存在，并且具有相應的屬性，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
以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作能帶來一定的幫助，如果有疑問大家可留言交流。
新聞熱點
疑難解答
