(Turn) The shell script code to determine whether the file exists

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
# Check if the file exists
# link：www.jb51.net
# date：2013/2/28  
 myPath="/var/log/httpd/"
myFile="/var /log/httpd/access.log"
 # The -x parameter here determines whether $myPath exists and whether it has executable permissions
if [ ! -x "$myPath"]; then
  mkdir "$myPath"
be
# The -d parameter here determines whether $myPath exists
if [ ! -d "$myPath"]; then
 mkdir "$myPath"
be
 # The -f parameter here determines whether $myFile exists
if [ ! -f "$myFile" ]; then
 touch "$myFile"
be
# Other parameters include -n, -n is to determine whether a variable has a value
if [ ! -n "$myVar" ]; then
 echo "$myVar is empty"
 exit 0
be
 # Check if two variables are equal
if [ "$var1" = "$var2" ]; then
 echo '$var1 eq $var2'
else
 echo '$var1 not eq $var2'
be