for in 格式
for 无$变量 in 字符串
do
$变量
done
| 一简单的字符串 枚举遍历法，利用for in格式对字符串按空格切份的功能
SERVICES="80 22 25 110 8000 23 20 21 3306 "
for x in $SERVICES
do
iptables -A INPUT -p tcp --dport $x -m state --state NEW -j ACCEPT
done
|
for variable in values --------字符串数组依次赋值
#!/bin/sh
for i in a b c 字符串列表A B C
字符串用空格分隔,没有括号,没有逗号, 然后循环将其依次赋给变量i
变量没有$
do
echo "i is $i"
done | [macg@machome ~]$ sh test.sh
i is a
i is b
i is c
|
for in 里，变量和*不等价
#!/bin/bash
for i in *.h ;
do
cat ${i}.h
done
| [macg@vm test]$ ./tip.sh
cat: *.h.h: No such file or directory
$i代表的是整个路径，而不是*.h里的.h前面的部分
| 改正
#!/bin/bash
for i in *.h
do
cat $i
done
| [macg@vm test]$ echo hahaha >>1.h
[macg@vm test]$ echo ha >>2.h
[macg@vm test]$ ./tip.sh
hahaha
ha
| 例2：
for i in /etc/profile.d/*.sh
do
$i
done
| $i代表的是/etc/profile.d/color.sh,
/etc/profile.d/alias.sh, /etc/profile.d/default.sh |
for in 对(命令行，函数)参数遍历
test()
{
local i
for i in $* ; do
echo "i is $i"
done
}
$*是字符串：以"参数1 参数2 ... " 形式保存所有参数
$i是变量i的应用表示
| [macg@machome ~]$ sh test.sh p1 p2 p3 p4
i is p1
i is p2
i is p3
i is p4
|
for in语句与通配符*合用,批量处理文件
批量改文件名
[root@vm testtip]# ls
aaa.txt ccc.txt eee.txt ggg.txt hhh.txt jjj.txt lll.txt nnn.txt
bbb.txt ddd.txt fff.txt go.sh iii.txt kkk.txt mmm.txt ooo.txt
| [root@vm testtip]# cat go.sh
for i in *.txt *.txt相当于一个字符串数组，依次循环赋值给i
do
mv "$i" "$i.bak"
done
| [root@vm testtip]# sh go.sh
[root@vm testtip]# ls
aaa.txt.bak ccc.txt.bak eee.txt.bak ggg.txt.bak hhh.txt.bak jjj.txt.bak lll.txt.bak nnn.txt.bak bbb.txt.bak ddd.txt.bak fff.txt.bak go.sh iii.txt.bak kkk.txt.bak mmm.txt.bak ooo.txt.bak
|
for in语句与` `和$( )合用，利用` `或$( )的将多行合为一行的缺陷，实际是合为一个字符串数组
for i in $(ls *.txt)
do
echo $i
done
| [macg@machome ~]$ sh test
111-tmp.txt
111.txt
22.txt
33.txt
| 或者说，利用for in克服` `和$( ) 的多行合为一行的缺陷
利用for in 自动对字符串按空格遍历的特性，对多个目录遍历
LIST="rootfs usr data data2"
for d in $LIST; do
mount /backup/$d
rsync -ax --exclude fstab --delete /$d/ /backup/$d/
umount /backup/$d
done
|
|