Shell 10 Process Control

If is judged if

#shell#!/bin/sha=5if [[ $a > 3 ]];then    echo "$a>3"fi#写成一行if [[ $a < 6 ]];then echo "$a>3";fi

5>3
5>3

If Else

#shell#!/bin/sha=5if [[ $a > 8 ]];then    echo "$a>8"else    echo "$a<8"fi

5<8

If elif Else

#shell#!/bin/sha=5if [[ $a > 5 ]];then    echo "$a>5"elif [ $a -eq 5 ];then    echo "$a=5"else    echo "$a<5"fi

5=5

For loop

#shell#!/bin/shfor i in `seq 1 5`;do    echo $idone

1
2
3
4
5

While statement

#shella=1while [ $a -lt 5 ];do    echo "$a"    let "a++"        #或者 a=`expr $a + 1`done

1
2
3
4

Infinite Loop while using: substitution condition

#shell#!/bin/shwhile : ;do    echo "hello"done

While condition is always true

#shell#!/bin/shwhile true;do    echo "hello"done

Using a For loop

#!/bin/shfor ((;;));do    echo "hello"done

Until cycle

#shell#!/bin/sha=0until [ $a -gt 10 ]; do    echo $a    let "a++"done

0
1
2
3
4
5
6
7
8
9
10

Case is a multi-select statement, each case statement matches a value with a pattern

#shell#!/bin/shread -p "请输入的你的名次:" numcase $num in    1) echo "武林盟主"    ;;    2) echo "五岳盟主"    ;;    3) echo "华山掌门"    ;;    *) echo "回家玩去"esac

Jump out of the loop break jump out of all loops

#shellwhile :;do    read -p "请输入1到5之间的数字：" num    case $num in        1|2|3|4|5) echo "你输入的数字为$num"        ;;        *) echo "你输入的数字不在1和5之间"            break        ;;    esacdone

Stop the loop after entering 6
Please enter a number from 1 to 5:5
The number you entered is 5.
Please enter a number from 1 to 5:4
The number you entered is 4.
Please enter a number from 1 to 5:6
The number you entered is not between 1 and 5.

Continue jump out of this cycle

#shellwhile :;do    read -p "请输入1到5之间的数字：" num    case $num in        1|2|3|4|5) echo "你输入的数字为$num"        ;;        *) echo "你输入的数字不在1和5之间"            continue            echo "游戏结束"        ;;    esacdone

Continue the next loop after entering 7
Please enter a number from 1 to 5:7
The number you entered is not between 1 and 5.
Please enter a number from 1 to 5:3
The number you entered is 3.
Please enter a number from 1 to 5:6
The number you entered is not between 1 and 5.

Esac case ends with EASC, each case branched with;; To break

Shell 10 Process Control