[Linux] Bash getopts用法等价物: 解析命令行选项

Overview

The getopts command in Bash is used for parsing command-line options and arguments in shell scripts. It simplifies the process of handling options, allowing scripts to accept flags and parameters in a standardized way.

Usage

The basic syntax of the getopts command is as follows:

getopts optstring variable

• optstring: A string that defines the valid options.
• variable: The name of the variable that will hold the option character.

Common Options

• -a: Indicates that the option requires an argument.
• -b: Used to specify a boolean flag.
• -c: Can be used to count occurrences of an option.

Common Examples

Example 1: Basic Option Parsing

This example shows how to parse a single option -a:

#!/bin/bash

while getopts "a" opt; do
  case $opt in
    a)
      echo "Option -a was triggered."
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      ;;
  esac
done

Example 2: Options with Arguments

In this example, we parse an option -f that requires an argument:

#!/bin/bash

while getopts "f:" opt; do
  case $opt in
    f)
      echo "File name provided: $OPTARG"
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      ;;
  esac
done

Example 3: Multiple Options

This example demonstrates how to handle multiple options:

#!/bin/bash

while getopts "ab:c:" opt; do
  case $opt in
    a)
      echo "Option -a was triggered."
      ;;
    b)
      echo "Option -b with argument: $OPTARG"
      ;;
    c)
      echo "Option -c with argument: $OPTARG"
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      ;;
  esac
done

Tips

• Always include a case for \? to handle invalid options gracefully.
• Use a colon (:) after an option in optstring to indicate that it requires an argument.
• Consider using shift after processing options to handle positional parameters if needed.