预备知识

内部字段分隔符（Internal Field Separator, IFS）

• IFS读取变量中的每一个条目

[root@shaofeng ~]# ./ifs.sh
Item: name
Item:  sex
Item:  rollno
Item:  location
[root@shaofeng ~]# cat ./ifs.sh
#!/bin/bash

export data="name, sex, rollno, location"
oldIFS=$IFS
IFS=, #now
for item in $data;
do
        echo Item: $item
done

实战演练

• ifs结合循环

[root@shaofeng ~]# ./ifs.sh
wo buai shaofeng
[root@shaofeng ~]# cat ./ifs.sh
#!/bin/bash

line="wo:ai:buai"
IFS=:
count=0
for item in $line;
do
 [ $count -eq 0 ] && user=$item;
 [ $count -eq 2 ] && do=$item;
 let count++;
done

echo $user $do shaofeng

• for循环

for var in list;
do
 commands;
done

• while循环

while condition
do
 commands;
done

• until循环，直到到达条件

[root@shaofeng ~]# ./util.sh
0
1
[root@shaofeng ~]# cat ./util.sh
#!/bin/bash

count=0
until [ $count -eq 2 ];
do
  echo $count
  let count++;
done