循环控制语句
循环控制语句：continue，break，shift
用于循环体中
continue
continue [N]：提前结束第N层的本轮循环，而直接进入下一轮判断；最内层为第1层
while CONDITION1;do
CMD1
...
if CONDITION2; then
continue
fi
CMDn
...
done
break
break[N]：提前结束第N层循环，最内层为第1层
while CONDITION1; do
CMD1
...
if CONDITION2; then
break
fi
CMDn
...
done
continue和break
continue：提前结束本次循环，提前进入下一轮循环，continue 2 跳出本次内层循环，进入外层循环
break：结束本次循环（整个），退出脚本
[root@centos SC]#vim test.sh
#!/bin/bash
for i in {1..10}
do
[ $i -eq 5 ] && break
echo i=$i
sleep 0.5
done
echo test is finished
~
▽
~
~
~
~
"test.sh" [New] 8L, 104C written
[root@centos SC]#chmod +x test.sh
[root@centos SC]#./test.sh
i=1
i=2
i=3
i=4
test is finished
[root@centos SC]#vim test.sh
#!/bin/bash
for i in {1..10}
do
[ $i -eq 5 ] && continue
echo i=$i
sleep 0.5
done
echo test is finished
~
~
~
~
~
~
~
"test.sh" 8L, 107C written
[root@centos SC]#./test.sh
i=1
i=2
i=3
i=4
i=6
i=7
i=8
i=9
i=10
test is finished
shift
shift[N]：用于将参量列表 list 左移指定次数，缺省为左移一次。
参量列表 list 一旦被移动，最左端的那个参数就从列表中删 除。while 循环遍历位置参量列表时，常用到 shift
./doit.sh a b c d e f g h
./shfit.sh a b c d e f g h
[root@centos SC]#vim doit.sh
#!/bin/bash
while [ $# -gt 0 ]
do
echo $*
shift
done
~
~
~
~
▽
~
~
~
[root@centos SC]#./doit.sh a b c d e f g h
a b c d e f g h
b c d e f g h
c d e f g h
d e f g h
e f g h
f g h
g h
h
[root@centos SC]#vim shift.sh
#!/bin/bash
until [ -z "$1" ]
do
echo "$1"
shift
done
echo
~
~
~
~
~
~
~
~
[root@centos SC]#./shfit.sh a b c d e f g h
-bash: ./shfit.sh: No such file or directory
[root@centos SC]#./shift.sh a b c d e f g h
a
b
c
d
e
f
g
h
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