shell 脚本如何判断文件是否存在

       在进行linux系统相关应用程序开发时，少不了要书写一些shell脚本，有时候要用到判断文件或者目录是否存在的脚本，本文笔者做一下笔记，已备后查。

shell判断文件是否存在的脚本如下：

//[ 与 ] 的前后必须有空格符
if [ -f /path/file.ext ] 
then 
     echo "The file exist"
else
     echo "The file doesn't exist"
fi

//判断某链接是否存在
if [ -L /path/link ] 
then 
    echo "The link exist"
else
    echo "The link doesn't exist"
fi

 其实shell对于文件册测试有好几种选项开关，现在例举如下：

表达式	测试含义
-a filepath	file exists. all files type
-b filepath	file exists and is a block special file.
-c filepath	file exists and is a character special file.
-d filepath	file exists and is a directory.
-e filepath	file exists (等同于 -a).
-f  filepath	file exists and is a regular file.
-g filepath	file exists and has its setgid(2) bit set.
-G filepath	file exists and has the same group ID as this process.
-k filepath	file exists and has its sticky bit set.
-L filepath	file exists and is a symbolic link.
-n filepath	string length is not zero.
-o filepath	Named option is set on.
-O filepath	file exists and is owned by the user ID of this process.
-p filepath	file exists and is a first in, first out (FIFO) special file or named pipe.
-r filepath	file exists and is readable by the current process.
-s filepath	file exists and has a size greater than zero.
-S filepath	file exists and is a socket.
-t filepath	file descriptor number fildes is open and associated with a terminal device.
-u filepath	file exists and has its setuid(2) bit set.
-w filepath	file exists and is writable by the current process.
-x filepath	file exists and is executable by the current process.