template-bash-command/README.md

Bash Template Command

This README.md is autogenerated.

This is a GitHub template repo that will be copied instead of forked to create a new Bash command with a command something like this:

gh repo create rwxrob/mycmd -p rwxrob/template-bash-command

This cmd inside can then be renamed and finished.

Naming Conventions

• Name repos containing single bash commands with cmd-
• Name template repos beginning with template-
• Start command functions with command_ to be completed
• Start command functions with command__ to not be completed

If you want to keep a command but hide it from users just add another underscore to the prefix which turns it into a hidden command, which will not be included in help documentation and tab completion, but will still be there.

Builtins and Utilities

A number of builtin and frequently used utility functions have been included for convenience. These save developers from adding other moronic things like sed and awk subprocesses. Obviously, not all of this is needed for many Bash scripts. Just remove what you do not need or want.

_initialize

The _initialize function is meant to contain initialization code and be placed at the beginning of the script to be found easily even though it is called at the bottom of the script (as bash requires).

_have

Returns true (0) if the first argument exists as an executable in the current PATH. Otherwise, return false (1).

_checkdep

Checks that the first argument exists as an executable in the current PATH. If so, returns true (0). If not, prints a generic error message in English and returns false (1). The "progressive enhancement" design principle requires minimal functionality using what is available and progressively upgrading based on what is detected.

_newest

Uses ls to return the newest file or directory in the specified directory.

_trim

Removes all whitespace ([:space:]) from the beginning and ending of a string without invoking a subprocess.

_filter

Reads the first argument or each line of standard input passing each individually as the first argument to the calling function one at a time. The UNIX philosophy requires all commands be filters whenever possible.

_buffer

Reads the first argument or all lines of standard input and then passes them to the calling function as the first argument. The UNIX philosophy requires all command be filters whenever possible.

_reduce

Takes the name of an array and a bash extended regular expression and prints only the array entries that match, one to a line suitable for converting back into an array with IFS=$'\n' or just as an in-memory grep replacement.

_jsonstr

Encodes first argument or all standard input into a single line of JSON text. This function depends on the jq command.

_urlencode

Encodes the first argument or all standard input using standard URL encoding suitable for passing to curl or whatever. This function has no external dependencies.

Dependencies

Required:

• Bash 4+

Optional:

• pandoc - for rich help docs
• jq - for json and anything that uses it

Justification

Bash is the dominant shell scripting language and the official default Linux interactive shell, which reduces cognitive overhead; every command line is a line of code that could be put into script as is. Bash scripts are at the core of cloud, containers, and Kubernetes. Bash 4+ with its associative array support, powerful regular expressions, and multiple ways of feeding data to loops easily covers the needs previously requiring Python and Perl scripts. Bash scripts are also much more powerful, safer, flexible, and performant than POSIX shell or Zsh.

Guidelines

• Write GitHub Flavored Markdown only
• Use present tense ("outputs" over "will output")
• Prefer term "output" and "display" over print
• Follow the naming conventions
• Use the official bash path: #!/bin/bash
• Use of #!/usr/bin/bash is outdated
• Using #!/usr/bin/env bash introduces unnecessary risk
• Explicitly export PATH in script when possible
• Always check script with shellcheck before releasing
• Always use bc for any floating point math

Legal

Copyright 2021 Rob Muhlestein rob@rwx.gg
Released under Apache-2.0 License
Please mention rwxrob.tv

The bar Command

cmd bar

Bar the things.

The config Command

cmd config
cmd config KEY
cmd config KEY VALUE
cmd config KEY ""
cmd config keys
cmd config val[ues]
cmd config dir[ectory]
cmd config path [file]
cmd config edit [file]
cmd config del[ete]

The config command is for reading, writing, and displaying standard open desktop configuration properties. Pass an empty string to delete a property.

Arguments

With no arguments outputs all the currently cached configuration settings.

With a single KEY argument fetches the value for that key and outputs it unless it is one of the following special (reserved) key names:

• dir* full path to config directory
• path full path to specific config file (default: values)
• edit opens config file in editor (default: editor or `$EDITOR)
• keys output the configuration keys, one per line
• val* output the configuration values, one per line
• del* if key argument then delete a specific key, otherwise prompt

With more than one argument the remaining arguments after the KEY will be combined into the VALUE and written to a values file in the configuration directory.

Configuration Directory

The configuration directory path relies on the following environment variables:

• EXE - defaults to name of currently running command (cmd)
• HOME - checked for $HOME/.config/$EXE/values
• XDG_CONFIG_HOME - overrides $HOME/.config
• CONFIG_DIR - full path to directory containing values file

The CONFIG_DIR always takes priority over anything else if set, but is never implied. If the directory does not exist it will be created the first time a value is set.

Configuration values File Format

The file (which is almost always located at ~/.config/cmd/values) uses the simplest possible format to facilitate standard UNIX parsing and filtering with any number of existing tools (and no jq dependency).

• One KEY=VALUE per line
• KEYs may be anything but the equal sign (=)
• VALUEs may be anything but line returns must be escaped

Note that this is not the same as Java properties and other similar format. It is designed for ultimate simplicity, efficiency, and portability.

The foo Command

Foos things.

The help Command

cmd help [COMMAND]

Displays specific help information. If no argument is passed displays general help information (main). Otherwise, the documentation for the specific argument keyword is displayed, which usually corresponds to a COMMAND name (but not necessarily). All documentation is written in GitHub Flavored Markdown and will displayed as a web page if pandoc and $HELP_BROWSER are detected, otherwise, just the Markdown is sent to $PAGER (default: more).

Also see readme and usage commands.

Generate README.md File

cmd readme > README.md

The readme command will output the embedded help documentation in raw GitHub Flavored Markdown suitable for use as a README.md file on GitHub or similar hosting service.

The some.config.setting Command

Get and set some.config.setting.

The usage Command

Displays a summary of usage.

---

Autogenerated Tue Aug 31 09:54:00 AM EDT 2021