判断文件是否存在的shell脚本代码

实现代码一、

#!/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 0
fi

# 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

实现代码二、

#shell判断文件夹是否存在

#如果文件夹不存在，创建文件夹
if [ ! -d "/myfolder" ]; then
 mkdir /myfolder
fi

#shell判断文件,目录是否存在或者具有权限

folder="/var/www/"
file="/var/www/log"

# -x 参数判断 $folder 是否存在并且是否具有可执行权限
if [ ! -x "$folder"]; then
 mkdir "$folder"
fi

# -d 参数判断 $folder 是否存在
if [ ! -d "$folder"]; then
 mkdir "$folder"
fi

# -f 参数判断 $file 是否存在
if [ ! -f "$file" ]; then
 touch "$file"
fi

# -n 判断一个变量是否有值
if [ ! -n "$var" ]; then
 echo "$var is empty"
 exit 0
fi

# 判断两个变量是否相等
if [ "$var1" = "$var2" ]; then
 echo '$var1 eq $var2'
else
 echo '$var1 not eq $var2'
fi

-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！