The GetoptLong class allows you to parse command line options similarly to the GNU getopt_long() C library call. Note, however, that GetoptLong is a pure Ruby implementation.
GetoptLong allows for POSIX-style options like --file as well as single letter options like -f
The empty option -- (two minus symbols) is used to end option processing. This can be particularly important if options have optional arguments.
Add this line to your application's Gemfile:
And then execute:
Or install it yourself as:
require 'getoptlong'
opts = GetoptLong.new(
[ '--help', '-h', GetoptLong::NO_ARGUMENT ],
[ '--repeat', '-n', GetoptLong::REQUIRED_ARGUMENT ],
[ '--name', GetoptLong::OPTIONAL_ARGUMENT ]
)
dir = nil
name = nil
repetitions = 1
opts.each do |opt, arg|
case opt
when '--help'
puts <<-EOF
hello [OPTION] ... DIR
-h, --help:
show help
--repeat x, -n x:
repeat x times
--name [name]:
greet user by name, if name not supplied default is John
DIR: The directory in which to issue the greeting.
EOF
when '--repeat'
repetitions = arg.to_i
when '--name'
if arg == ''
name = 'John'
else
name = arg
end
end
end
if ARGV.length != 1
puts "Missing dir argument (try --help)"
exit 0
end
dir = ARGV.shift
Dir.chdir(dir)
for i in (1..repetitions)
print "Hello"
if name
print ", #{name}"
end
puts
end
Example command line:
hello -n 6 --name -- /tmp
After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.
Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/getoptlong.
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