shell编程基础

for c in a b c d e f g;do echo $c; done 按顺序输出

for c in a b c d e f g;do tar czvf install.log.$c.tar.gz install.log ; done

for c in {a..g}; do echo $c; done 和上面的一样

seq 1 10 列数字的

for i in {1..10}; do echo $i; done

 

 

字符串变量实例
str='I love linux. I love unix too.'

echo ${str} 计算字符串长度

echo ${str:5} 截取str从第五个字符到串尾

echo ${str:7:5} 截取str从第七个字符开始的第五个字符

echo ${str#I love} 删除开始的字符串

echo ${str#I*.} 删除开始I到.的所有字符，最短匹配

echo ${str##I*} 删除开始I到.的所有字符，最长匹配

 

test 是测试的意思

shell 编程:
单分支
#!/bin/bash
filename=/myshell/test1
if test -f $filename; then
echo 'The file is exist.'
fi

双分支
#!/bin/bash
filename=/myshell/test1
if test -f $filename; then
echo 'The file is exist.'
else
echo 'The file is not exist.'
fi

 

#!/bin/bash
filename=/myshell/test2
if [ -f $filename ] ; then
echo 'The file is exist.'
else
echo 'The file is not exist.'
fi

 

 

判断
#!/bin/bash
a=this
b=there
[ $a != $b ]&&echo Yes || echo No

 

#!/bin/bash
filename=/myshell/test3
test -f $filename && echo 'exist' || echo 'not exist'
test -d $filename && echo 'exist' || echo 'not exist'
test -r $filename && echo 'exist' || echo 'not exist'
test -w $filename && echo 'exist' || echo 'not exist'
test -x $filename && echo 'exist' || echo 'not exist'

 

多分支
#!/bin/bash
echo 'Please input your number.'
read number
if [ $number == 1 ] ; then
echo 'Your input number is 1 .'
elif [ $number == 2 ] ; then
echo 'Your input number is 2 .'
elif [ $number == 3 ] ; then
echo 'Your input number is 3 .'
else
echo 'I dont know what you input.'
fi

 

echo 'Please input your hardware.'
read hd
if [ $hd == cpu ] ; then
echo 'Your cpu info is .'
cat /proc/cpuinfo
elif [ $hd == mem ] ; then
echo 'Your mem info is .'
cat /proc/meminfo
elif [ $hd == hard ] ; then
echo 'Your harddisk info is .'
df -h
else
echo 'I dont know what you input.'
fi

 

echo 'Please input your number.'
read number
case $number in
1)
echo 'Your input number is 1 .';;
2)
echo 'Your input number is 2 .';;
3)
echo 'Your input number is 3 .';;
*)
echo 'I dont know what you input.';;
esac

 

echo 'Please input kemu.'
read kemu
case $kemu in
shuxue)
echo 'Your input is shuxue.';;
english)
echo 'Your input is english .';;
yuwen)
echo 'Your input is yuwen .';;
*)
echo 'I dont know what you input.';;
esac

 

 

while循环:

#!/bin/bash
# [] -eq -ne -gt -ge -lt -le
#( () ) == != > >= < <=
#program summary

i=10
#while (($i>5)) ;do
while [ $i -gt 5 ] ;do
echo $i;
#if [ $i -eq 8 ] ;then
# echo 'The number is 8.'
#fi
((i--)) ;
done;

until循环：

#!/bin/bash

a=10
until (($a<0)) ;do
echo $a;
((a--)) ;
done;

 

 

 

for循环：
#!/bin/bash
for((i=1;i<=10;i++));do
echo $i;
done;

#!/bin/bash
echo 'Please input an numer.'
read number
for((i=1;i<=$number;i++));do
echo $i;
done;

 

函数：

#!/bin/bash
function print(){
echo "Your input is $x"
}

echo "This program will print you selection!"

case $x in
"one")
print 1;;
"two")
print 2;;
"three")
print 3;;
*)
print "Usage $0 one|two|three";;
esac