1. for 循环语句:
for 的两种常用写法:
写法 (1):
for var in 1 2 3 4 5 (ps: 或者 for var in $(seq 1 5) 或者 for var in {1..5})
- do
- echo -n "$val"
- done
写法 (2):
for((i=0;i<10;i++)) ( ps: 必须是 for(( )) )
- {
- let "val=i%2"
- if [ $val -ne 0 ]; then
- echo "${i} is a odd number"
- fi
- }
2. while 循环语句:
while 常用写法:
写法 (1):
- while read line # ( ps:while 读取是按行读, 常用于文本按行读取 )
- do
- if [ "$line" -eq 5 ]; then
- echo "5"
- break
- fi
- done # ( ps: 写成 done < data.txt 则重定向从 data.txt 中按行读取数据)
写法 (2):
- res=10
- while [ $res -gt 0 ]
- do
- echo -n "$res"
- let "res-=1"
- done
- echo "done"
Shell 编程 ------ 循环语句
来源: http://www.bubuko.com/infodetail-2486574.html