https://github.com/purarue/havecmd

A template for bash scripts, to provide a nicer interface to check for the presence of external commands on the users $PATH
https://github.com/purarue/havecmd

bash dependency-manager scripting template

Last synced: about 1 month ago
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A template for bash scripts, to provide a nicer interface to check for the presence of external commands on the users $PATH

• Host: GitHub
• URL: https://github.com/purarue/havecmd
• Owner: purarue
• License: apache-2.0
• Created: 2020-09-18T14:11:12.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2024-11-12T03:57:07.000Z (3 months ago)
• Last Synced: 2024-11-12T04:29:26.434Z (3 months ago)
• Topics: bash, dependency-manager, scripting, template
• Language: Shell
• Homepage:
• Size: 27.3 KB
• Stars: 3
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# havecmd

A template for `bash` scripts, to provide a nicer interface to check for the presence of external commands on the users `$PATH`.

This isn't a dependency, because the whole point of this script is to check for dependencies. So, this is vendorized; whenever I'm writing a substantial bash script that depends on external commands that may or may not be installed, I copy the `./template` script and start from there.

Easiest way to understand the interface is to read it:

```shell

#!/usr/bin/env bash

# Template from https://github.com/purarue/havecmd

# get the name of this script

declare script_name

script_name="$(basename "${BASH_SOURCE[0]}")"

# function to verify an external command is installed

havecmd() {

	local BINARY ERRMSG

	BINARY="${1:?Must provide command to check}"

	# the command is on the users $PATH, exit with success

	if command -v "${BINARY}" >/dev/null 2>&1; then

		return 0

	else

		# construct error message

		ERRMSG="'${script_name}' requires '${BINARY}', could not find that on your \$PATH"

		[[ -n "$2" ]] && ERRMSG="${ERRMSG}. $2"

		printf '%s\n' "${ERRMSG}" 1>&2

		return 1

	fi

} && export -f havecmd

# export the function, it is defined in any other bash scripts this calls

# If the first argument isn't available on the users $PATH

# print an error and the second argument (installation instructions), if given

# set the -e flag; this script exits if any of the dependencies aren't satisfied

set -e

# Examples

havecmd python

havecmd fd 'See installation instructions at https://github.com/sharkdp/fd'

havecmd wait-for-internet "Install it with 'cargo install --git https://github.com/purarue/wait-for-internet'"

havecmd pmark

set +e

# at this point, all dependencies are satisfied

main() {

	echo "ran '${script_name}' with arguments '$*'"

	return 0

}

main "$@" || exit $?

```