function::cmdline_arg - Linux

Overview

cmdline_arg is a powerful Linux command that allows users to access and manipulate individual command-line arguments within a script or program. It provides a flexible way to parse and interact with user inputs, making it a versatile tool for various scripting and automation tasks.

Syntax

cmdline_arg [OPTIONS] NUMBER [DEFAULT]

Options/Flags

  • -h, –help: Display help and usage information.
  • -s, –space-separated: Treat arguments as space-separated instead of the default line-breaking.
  • -v, –verbose: Print additional information and debugging output.

Examples

Retrieve the first command-line argument:

RESULT=$(cmdline_arg 1)
# $RESULT contains the first argument passed to the program

Parse arguments using space-separated values:

cmdline_arg -s 2 "Default Argument"
# Retrieve the third space-separated argument or "Default Argument" if not provided

Handle missing arguments with a default value:

cmdline_arg 3 "Default Value"
# Retrieve the fourth argument or "Default Value" if it's missing

Common Issues

  • Incorrect argument numbers: Ensure you specify valid argument numbers. Trying to access a non-existent argument will result in an error.
  • Unhandled empty arguments: By default, cmdline_arg skips empty arguments. If you need to handle empty arguments, use the -s flag to treat them as space-separated values.

Integration

cmdline_arg can be integrated with other commands using pipelines and command substitution. For example:

echo "Argument 1 Argument 2" | cmdline_arg -s 2
# Retrieve the second space-separated argument from the piped input

Related Commands

  • basename: Extract the filename from a path.
  • dirname: Extract the directory name from a path.
  • sed: Perform text substitution and manipulation.