shell或bash中的 判断文件是否存在的脚本语法
2014-02-20 21:06
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比如这样判断:
for i in 0 1 2; do
if [ -e /sys/class/net/ech$i ]; then
ifconfig eth$i
break
fi
done
语法分析--------------------------------
-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!
---------------------或者:
#!/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
---------------------其他的:
shell语法好麻烦的,一个循环都弄了一会 ,找了几个不同的方法来实现输出1-100间可以被3整除的数
1.用(())
#!/bin/bash ///《---------------这里是bash
clear
for((i=1;i<100;i++))
for
do
if((i%3==0))
then
echo $i
continue
fi
done
2.使用`seq 100`
#!/bin/bash
clear
for i in `seq 100`
do
if((i%3==0))
then
echo $i
continue
fi
done
3.使用while
#!/bin/bash
clear
i=1
while(($i<100))
do
if(($i%3==0))
then
echo $i
fi
i=$(($i+1))
done
for i in 0 1 2; do
if [ -e /sys/class/net/ech$i ]; then
ifconfig eth$i
break
fi
done
语法分析--------------------------------
-f 和-e的区别
Conditional Logic on Files
-a file exists.
-b file exists and is a block special file.
-c file exists and is a character special file.
-d file exists and is a directory.
-e file exists (just the same as -a).
-f file exists and is a regular file.
-g file exists and has its setgid(2) bit set.
-G file exists and has the same group ID as this process.
-k file exists and has its sticky bit set.
-L file exists and is a symbolic link.
-n string length is not zero.
-o Named option is set on.
-O file exists and is owned by the user ID of this process.
-p file exists and is a first in, first out (FIFO) special file or
named pipe.
-r file exists and is readable by the current process.
-s file exists and has a size greater than zero.
-S file exists and is a socket.
-t file descriptor number fildes is open and associated with a
terminal device.
-u file exists and has its setuid(2) bit set.
-w file exists and is writable by the current process.
-x file exists and is executable by the current process.
-z string length is zero.
是用 -s 还是用 -f 这个区别是很大的!
---------------------或者:
#!/bin/sh
# 判断文件是否存在
# link:www.jb51.net
# date:2013/2/28
myPath="/var/log/httpd/"
myFile="/var /log/httpd/access.log"
# 这里的-x 参数判断$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
---------------------其他的:
shell语法好麻烦的,一个循环都弄了一会 ,找了几个不同的方法来实现输出1-100间可以被3整除的数
1.用(())
#!/bin/bash ///《---------------这里是bash
clear
for((i=1;i<100;i++))
for
do
if((i%3==0))
then
echo $i
continue
fi
done
2.使用`seq 100`
#!/bin/bash
clear
for i in `seq 100`
do
if((i%3==0))
then
echo $i
continue
fi
done
3.使用while
#!/bin/bash
clear
i=1
while(($i<100))
do
if(($i%3==0))
then
echo $i
fi
i=$(($i+1))
done
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