一，介绍

image.png

二，练习

[root@127 shell_demo]# vim parameter.sh
[root@127 shell_demo]# bash parameter.sh 
arg1=, arg2=, arg3=, arg4=, arg5=, arg6=, count=0
arg1=, arg2=, arg3=, arg4=, arg5=, arg6=, count=0
arg1=, arg2=, arg3=, arg4=, arg5=, arg6=, count=0
arg1=, arg2=, arg3=, arg4=, arg5=, arg6=, count=0
[root@127 shell_demo]# bash parameter.sh a b c 1 2 3
arg1=a, arg2=b, arg3=c, arg4=1, arg5=2, arg6=3, count=6
arg1=b, arg2=c, arg3=1, arg4=2, arg5=3, arg6=, count=5
arg1=1, arg2=2, arg3=3, arg4=, arg5=, arg6=, count=3
arg1=2, arg2=3, arg3=, arg4=, arg5=, arg6=, count=2
[root@127 shell_demo]# cat parameter.sh 
#!/bin/bash
# 功能描述：演示shift命令的作用，左移位置参数

echo "arg1=$1, arg2=$2, arg3=$3, arg4=$4, arg5=$5, arg6=$6, count=$#"
shift
echo "arg1=$1, arg2=$2, arg3=$3, arg4=$4, arg5=$5, arg6=$6, count=$#"
shift 2
echo "arg1=$1, arg2=$2, arg3=$3, arg4=$4, arg5=$5, arg6=$6, count=$#"
shift 1
echo "arg1=$1, arg2=$2, arg3=$3, arg4=$4, arg5=$5, arg6=$6, count=$#"
[root@127 shell_demo]# vim empty.sh
[root@127 shell_demo]# touch a.txt b.txt
[root@127 shell_demo]# echo "111" > 1.txt
[root@127 shell_demo]# echo "222" > 2.txt
[root@127 shell_demo]# mkdir test
[root@127 shell_demo]# bash empty.sh a.txt 1.txt b.txt 2.txt test/
a.txt 为空文件，正在删除该文件. 
1.txt为非空文件。
b.txt 为空文件，正在删除该文件. 
2.txt为非空文件。
test/为文件夹。
[root@127 shell_demo]# cat empty.sh 
#!/bin/bash
# 功能描述：读取位置参数，测试是否空文件并删除空文件

if [ $# -eq 0 ]; then
  echo "用法：$0 文件名..."
  exit 1
fi

# 测试位置变量个数，个数为0时循环结束
while (($#)); do
  if [ ! -s $1 ]; then
    echo -e "\033[31m$1 为空文件，正在删除该文件. \033[0m"
    rm -rf $1
  else
    [ -f $1 ] && echo -e "\033[32m$1为非空文件。\033[0m"
    [ -d $1 ] && echo -e "\033[32m$1为文件夹。\033[0m"
  fi
  shift
done