Lightweight and flexible library for writing command-line apps in Ruby.
Add this line to your application's Gemfile:
And then execute:
Or install it yourself as:
$ gem install mercenary
Note: Mercenary may not work with Ruby < 1.9.3.
Creating programs and commands with Mercenary is easy:
Mercenary.program(:jekyll) do |p| p.version Jekyll::VERSION p.description 'Jekyll is a blog-aware, static site generator in Ruby' p.syntax "jekyll <subcommand> [options]" p.command(:new) do |c| c.syntax "new PATH" # do not include the program name or super commands c.description "Creates a new Jekyll site scaffold in PATH" c.option 'blank', '--blank', 'Initialize the new site without any content.' c.action do |args, options| Jekyll::Commands::New.process(args, blank: options['blank']) end end p.command(:build) do |c| c.syntax "build [options]" c.description "Builds your Jekyll site" c.option 'safe', '--safe', 'Run in safe mode' c.option 'source', '--source DIR', 'From where to collect the source files' c.option 'destination', '--dest DIR', 'To where the compiled files should be written' c.action do |_, options| Jekyll::Commands::Build.process(options) end end # Bring in command bundled in external gem begin require "jekyll-import" JekyllImport.init_with_program(p) rescue LoadError end p.default_command(:build) end
All commands have the following default options:
-h/--help- show a help message
-v/--version- show the program version
-t/--trace- show the full backtrace when an error occurs
Creates and executes a program. Accepts two arguments:
name- program name as a Symbol
block- the specification for the program, passed the program instance as an argument.
Example is above, under the heading Usage.
Program is a subclass of
Command, so it has all of the methods documented
below as well as those for
Fetches the program configuration hash.
Create a new command. Accepts one argument:
name- the name of your command, as a symbol
Sets or gets the version of the command. Accepts an optional argument:
version- (optional) the version to set for the command. If present, this becomes the new version for the command and persists.
Sets or gets the syntax of the command. Built on parent syntaxes if a parent exists. Accepts one optional argument:
syntax- (optional) the syntax to set for the command. Will inherit from the parent commands or program. Usually in the form of
"command_name <SUBCOMMAND> [OPTIONS]"
When a parent command exists, say
supercommand, with syntax set as
supercommand <SUBCOMMAND> [OPTIONS], the syntax of the command in question
supercommand command_name <SUBCOMMAND> [OPTIONS] with both
[OPTIONS] stripped out. Any text between
] will be stripped from parent command syntaxes. The purpose
of this chaining is to reduce redundancy.
Sets or gets the description of the command. Accepts one optional argument:
desc- (optional) the description to set for the command. If provided, will override any previous description set for the command.
Sets or gets the default subcommand of the command to execute in the event no subcommand is passed during execution. Accepts one optional argument:
command_name- (optional) the
Symbolname of the subcommand to be executed. Raises an
ArgumentErrorif the subcommand doesn't exist. Overwrites previously-set default commands.
Adds a new option to the command. Accepts many arguments:
config_key- the configuration key that the value of this option maps to.
*options- all the options, globbed, to be passed to
OptionParser, namely the switches and the option description. Usually in the format
"-s", "--switch", "Sets the 'switch' flag".
Valid option calls:
cmd.option 'config_key', '-c', 'Sets the "config" flag' cmd.option 'config_key', '--config', 'Sets the "config" flag' cmd.option 'config_key', '-c', '--config', 'Sets the "config" flag.' cmd.option 'config_key', '-c FILE', '--config FILE', 'The config file.' cmd.option 'config_key', '-c FILE1[,FILE2[,FILE3...]]', '--config FILE1[,FILE2[,FILE3...]]', Array, 'The config files.'
Notice that you can specify either a short switch, a long switch, or both. If
you want to accept an argument, you have to specify it in the switch strings.
The class of the argument defaults to
String, but you can optionally set a
different class to create, e.g.
Array, if you are expecting a particular class
in your code from this option's value. The description is also optional, but
it's highly recommended to include a description.
Specifies an alias for this command such that the alias may be used in place of the command during execution. Accepts one argument:
cmd_name- the alias name for this command as a
cmd.alias(:my_alias) # Now `cmd` is now also executable via "my_alias"
Specifies a block to be executed in the event the command is specified at runtime. The block is given two arguments:
args- the non-switch arguments given from the command-line
options- the options hash built via the switches passed
Note that actions are additive, meaning any new call to
result in another action to be executed at runtime. Actions will be executed in
the order they are specified in.
cmd.action do |args, options| # do something! end
Access the logger for this command. Useful for outputting information to STDOUT. Accepts one optional argument:
level- (optional) the severity threshold at which to begin logging. Uses Ruby's built-in
Log level defaults to
cmd.logger(Logger::DEBUG) cmd.logger.debug "My debug message." cmd.logger.info "My informative message." cmd.logger.warn "ACHTUNG!!" cmd.logger.error "Something terrible has happened." cmd.logger.fatal "I can't continue doing what I'm doing."
Creates a new subcommand for the current command. Accepts two arguments:
cmd_name- the command name, as a Symbol
block- the specification of the subcommand in a block
my_command.command(:my_subcommand) do |subcmd| subcmd.description 'My subcommand' subcmd.syntax 'my_subcommand [OPTIONS]' # ... end
- Fork it
- Create your feature branch (
git checkout -b my-new-feature)
- Commit your changes (
git commit -am 'Add some feature')
- Push to the branch (
git push origin my-new-feature)
- Create new Pull Request