#Bash 的 getopts 命令

getopts OPTSTRING NAME [ARG]...

功能

解析选项参数。

getopts 每次解析一个参数，将其放入 $NAME变量中，然后将参数索引的变量 OPTIND 加一。

选项附带的参数会存入 OPTARG 变量中

如果解析到 PTSTRIN 中不包含的选项，$NAME 变量会被设为 ?。

每次调用 shell 或 shell 脚本时，OPTIND 都会被初始化为 1。

类型

Bash 内置命令。

参数

OPTSTRING - 选项字符串；用冒号（:）后缀表示选项需要附带参数
NAME - 接收选项的变量名称
ARG - 要解析的参数列表；默认为 $@（当前命令的全部参数）

#示例

#!/usr/bin/bash

while getopts "ab:c" OPT; do    # 支持 -a -b -c 三个选项，其中 -b 需要附带参数
  case $OPT in
    a)
      echo "选项 -a"
      ;;
    b)
      echo "选项 -b，参数是 $OPTARG"
      ;;
    c)
      echo "选项 -c"
      ;;
  esac
done

shift $((OPTIND - 1))           # 提取剩余参数
echo 剩余参数：$@

运行结果：

$ ./demo.sh -c -b hello world
选项 -c
选项 -b，参数是 hello
剩余参数：world

#相关命令

命令	说明
getopt	解析命令行参数

#推荐阅读

getopts(1p) — Linux manual page

#手册

getopts: getopts optstring name [arg ...]
    Parse option arguments.

    Getopts is used by shell procedures to parse positional parameters
    as options.

    OPTSTRING contains the option letters to be recognized; if a letter
    is followed by a colon, the option is expected to have an argument,
    which should be separated from it by white space.

    Each time it is invoked, getopts will place the next option in the
    shell variable $name, initializing name if it does not exist, and
    the index of the next argument to be processed into the shell
    variable OPTIND.  OPTIND is initialized to 1 each time the shell or
    a shell script is invoked.  When an option requires an argument,
    getopts places that argument into the shell variable OPTARG.

    getopts reports errors in one of two ways.  If the first character
    of OPTSTRING is a colon, getopts uses silent error reporting.  In
    this mode, no error messages are printed.  If an invalid option is
    seen, getopts places the option character found into OPTARG.  If a
    required argument is not found, getopts places a ':' into NAME and
    sets OPTARG to the option character found.  If getopts is not in
    silent mode, and an invalid option is seen, getopts places '?' into
    NAME and unsets OPTARG.  If a required argument is not found, a '?'
    is placed in NAME, OPTARG is unset, and a diagnostic message is
    printed.

    If the shell variable OPTERR has the value 0, getopts disables the
    printing of error messages, even if the first character of
    OPTSTRING is not a colon.  OPTERR has the value 1 by default.

    Getopts normally parses the positional parameters, but if arguments
    are supplied as ARG values, they are parsed instead.

    Exit Status:
    Returns success if an option is found; fails if the end of options is
    encountered or an error occurs.

#Bash 的 getopts 命令

#示例

#相关命令

#推荐阅读

#手册

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