Shell中获取参数

如果只需要传入参数，基本上可以使用$n来取参数，注意n是从1开始的整数

$0 指向的是脚本的名字

$ cat myscript
#!/bin/bash
echo "First arg: $1"
echo "Second arg: $2"
$ ./myscript hello world
First arg: hello
Second arg: world

但是有时需要使用Option来解析参数，并打印帮助信息，下面给出一个简单的例子

#!/bin/bash

helpFunction()
{
   echo ""
   echo "Usage: $0 -a parameterA -b parameterB -c parameterC"
   echo -e "\t-a Description of what is parameterA"
   echo -e "\t-b Description of what is parameterB"
   echo -e "\t-c Description of what is parameterC"
   exit 1 # Exit script after printing help
}

while getopts "a:b:c:" opt
do
   case "$opt" in
      a ) parameterA="$OPTARG" ;;
      b ) parameterB="$OPTARG" ;;
      c ) parameterC="$OPTARG" ;;
      ? ) helpFunction ;; # Print helpFunction in case parameter is non-existent
   esac
done

# Print helpFunction in case parameters are empty
if [ -z "$parameterA" ] || [ -z "$parameterB" ] || [ -z "$parameterC" ]
then
   echo "Some or all of the parameters are empty";
   helpFunction
fi

# Begin script in case all parameters are correct
echo "$parameterA"
echo "$parameterB"
echo "$parameterC"