判断文件是否存在的shell脚本代码

转载地址：http://www.jb51.net/article/34330.htm
-f 和-e的区别
Conditional Logic on Files
-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.
是用 -s 还是用 -f 这个区别是很大的！
实例代码：

#!/bin/sh# 判断文件是否存在# link：www.jb51.net# date：2013/2/28   myPath="/var/log/httpd/"myFile="/var /log/httpd/access.log"  # 这里的-x 参数判断$myPath是否存在并且是否具有可执行权限if [ ! -x "$myPath"]; then  mkdir "$myPath"fi# 这里的-d 参数判断$myPath是否存在if [ ! -d "$myPath"]; then mkdir "$myPath"fi  # 这里的-f参数判断$myFile是否存在if [ ! -f "$myFile" ]; then touch "$myFile"fi# 其他参数还有-n,-n是判断一个变量是否是否有值if [ ! -n "$myVar" ]; then echo "$myVar is empty" exit 0fi  # 两个变量判断是否相等if [ "$var1" = "$var2" ]; then echo '$var1 eq $var2'else echo '$var1 not eq $var2'fi