shell 判断某文件或链接存在

只给出一个例子，仅供参考使用

if [ -f /home/test.txt ] //前后记得有空格
then 
     echo "file exist"
else
     echo "file doesn't exist"
fi


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

使用脚本判断其他，如文件是否可读等参考http://www.cnblogs.com/sunyubo/archive/2011/10/17/2282047.html。

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