在shell script中使用sed命令显示帮助信息

脚本实例

###
### my-script — does one thing well
###
### Usage:
###   my-script <input> <output>
###
### Options:
###   <input>   Input file to read.
###   <output>  Output file to write. Use '-' for stdout.
###   -h        Show this message.

help() {
    sed -rn 's/^### ?//;T;p' "$0"
}

if [[ $# == 0 ]] || [[ "$1" == "-h" ]]; then
    help
    exit 1
fi

sed命令说明：

sed -rn 's/^### ?//;T;p' "$0"

$0：本脚本的文件名；
-r：启用正则表达式；
n：屏蔽默认输出；
s/^### ?//：匹配### 开头的行，并删掉### ；

测试

[root@test ~]# ./aa.sh -h

my-script — does one thing well

Usage:
  my-script <input> <output>

Options:
  <input>   Input file to read.
  <output>  Output file to write. Use '-' for