三分钟掌握linux shell脚本流程控制语法

#!/bin/bash

if [ $1 == $2 ];then
   echo "a == b"
elif [ $1 -gt $2 ];then
   echo "a > b"
elif [ $1 -lt $2 ];then
   echo "a < b"
else
   echo "error"
fi

#!/bin/bash

for loop in 1 2 3 4 5
do
    echo "The value is: $loop"
done

#!/bin/bash
i=0
while [[ $i<3 ]]
do
    echo $i
    let "i++"
done

#!/bin/bash
echo 'press <CTRL-D> exit'
while read num
do
    echo "you input is $num"
done

while true
do
    command
done

for (( ; ; ))
do
    command
done

#!/bin/bash
case $1 in
    1) echo 'You have chosen 1'
    ;;
    2) echo 'You have chosen 2'
    ;;
    *) echo 'You did not enter a number between 1 and 2'
    ;;
esac

case 值 in
模式1)
    command1
    command2
    ...
    commandN
    ;;
模式2）
    command1
    command2
    ...
    commandN
    ;;
esac