[shell]简单的shell提示和参数脚本

 该shell脚本有如下点：

• bash or dash
• case语句的写法
• 脚本help写法
• 参数是否为空的写法
• 算数运算的写法

#! /bin/bash
case "$1" in
    -h|--help|?)
    echo "Usage: 1st arg:pin name, 2st arg:reset time"
    echo "1st arg pin name:lte-reset,zigbee-reset"
    echo "2st arg reset time in ms"
    exit 0 
;;
esac

if [ ! -n "$1" ]; then
    echo "pls input 1st arg"
    exit
fi


if [ ! -n "$2" ]; then
    echo "pls input 2st arg"
    exit
fi

echo 0 > /home/gpio/$1
time=$[ $2 * 1000 ] 
echo $time > /home/gpio/$1

echo "you reset $1 with $2ms"

下面的脚本：

• 多条case分支
• 字符串比较

#! /bin/bash

USRPWM_DIR="/home/pwm"

case "$1" in
    -h|--help|?)
    echo "Usage1:1st arg:disable, enable"
    echo "Usage2:1st arg:period in us, 2st arg duty in us"
    exit
;;
    enable|disable)
    if [ "$1" == "enable" ] ; then
    echo "enable power charge"
        echo 1 > $USRPWM_DIR/power-charge/enable
    exit
    else
     echo "disable power charge"
        echo 0 > $USRPWM_DIR/power-charge/enable
    exit
    fi 
;;
esac

if [ ! -n "$1" ] ; then
    echo "pls input 1st arg: period with us"
    exit
fi
if [ ! -n "$2" ] ; then
    echo "pls input 2st arg: duty with us"
    exit
fi

arg1=$[ $1 * 1000 ]
arg2=$[ $2 * 1000 ]

echo $arg1 > $USRPWM_DIR/power-charge/period
echo $arg2 > $USRPWM_DIR/power-charge/duty_cycle
echo 1 > $USRPWM_DIR/power-charge/enable