getopt_long - Linux

Overview

getopt_long is a POSIX utility used for parsing command-line arguments. It provides a consistent and flexible way to parse complex arguments, including long options and short options with optional arguments.

Syntax

getopt_long [options] -- program [options] args...

Options/Flags

  • -o, –options: Specifies a list of short options. Each option is followed by a colon (:) if it takes an argument.
  • –longoptions: Specifies a list of long options. Each option is prefixed with two dashes (–).
  • -l, –name: Specifies the name of the program to be parsed.
  • -r, –required: Specifies a required argument for a short option.
  • -h, –help: Prints a help message.
  • –version: Prints the program version.

Examples

Simple Example:

getopt_long -o a:b --longoptions arg1:,arg2: -- arg1 value1 arg2 value2

This command parses the following arguments:

  • Short option -a with argument value1.
  • Long option --arg1 with argument value1.
  • Long option --arg2 with argument value2.

Complex Example:

getopt_long -o a:b:c --longoptions arg1:,arg2:,arg3 --required -- arg1 value1 arg2 value2 --arg3

This command parses the following arguments:

  • Short option -a with argument value1.
  • Short option -b with argument value2.
  • Long option --arg1 with argument value1.
  • Long option --arg2 with argument value2.
  • Long option --arg3 without an argument.

Common Issues

  • Missing Arguments: Ensure that required arguments are provided for both short and long options.
  • Unknown Options: Specify valid options/flags using the -o or --longoptions parameters.
  • Invalid Arguments: Verify that arguments passed to options are of the correct type and format.

Integration

getopt_long can be integrated with other commands to enhance argument parsing and scripting capabilities. For example:

find / -name *.txt | xargs -I {} grep -E 'pattern' {} | getopt_long -o s:n: --longoptions search:,num-lines: -- search pattern --num-lines 10

This command searches for .txt files containing the specified pattern and prints the first 10 matching lines.

Related Commands

  • getopt: A simpler option parsing utility for POSIX systems.
  • argparse: A comprehensive argument parsing library for Python.
  • commander.js: A Node.js package for parsing command-line arguments.