for in 格式
for 無$變量 in 字符串
do
$變量
done
| 一簡單的字符串 枚舉遍歷法，利用for in格式對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 $x -m state --state NEW -j ACCEPT
done
|
for variable in values --------字符串數(shù)組依次賦值
#!/bin/sh
for i in a b c 字符串列表A B C
字符串用空格分隔,沒有括號,沒有逗號, 然后循環(huán)將其依次賦給變量i
變量沒有$
do
echo "i is $i"
done | [macg@machome ~]$ sh test.sh
i is a
i is b
i is c
|
for in 里，變量和*不等價
#!/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代表的是整個路徑，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 對(命令行，函數(shù))參數(shù)遍歷
test()
{
local i
for i in $* ; do
echo "i is $i"
done
}
$*是字符串：以"參數(shù)1 參數(shù)2 ... " 形式保存所有參數(shù)
$i是變量i的應(yīng)用表示
| [macg@machome ~]$ sh test.sh p1 p2 p3 p4
i is p1
i is p2
i is p3
i is p4
|
for in語句與通配符*合用,批量處理文件
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相當于一個字符串數(shù)組，依次循環(huán)賦值給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語句與` `和$( )合用，利用` `或$( )的將多行合為一行的缺陷，實際是合為一個字符串數(shù)組
for i in $(ls *.txt)
do
echo $i
done
| [macg@machome ~]$ sh test
111-tmp.txt
111.txt
22.txt
33.txt
| 或者說，利用for in克服` `和$( ) 的多行合為一行的缺陷
利用for in 自動對字符串按空格遍歷的特性，對多個目錄遍歷
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
|
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