ruby, gem: update page; irb, rake: add page (#10412)

* gem: update page

* Use `snake_case` for placeholders
* Update the documentation URL

* ruby: move `irb` example to a separate page

* rake: add page

* ruby: reference other ruby-related pages

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

* irb: standard input => `stdin` (#10436)

---------

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/gem.md

@@ -1,7 +1,7 @@
 # gem
 
-> Interact with the package manager for the Ruby programming language.
-> More information: <https://rubygems.org>.
+> A package manager for the Ruby programming language.
+> More information: <https://guides.rubygems.org>.
 
 - Search for remote gem(s) and show all available versions:
 
@@ -9,19 +9,19 @@
 
 - Install the latest version of a gem:
 
-`gem install {{gemname}}`
+`gem install {{gem_name}}`
 
-- Install specific version of a gem:
+- Install a specific version of a gem:
 
-`gem install {{gemname}} --version {{1.0.0}}`
+`gem install {{gem_name}} --version {{1.0.0}}`
 
 - Install the latest matching (SemVer) version of a gem:
 
-`gem install {{gemname}} --version '~> {{1.0}}'`
+`gem install {{gem_name}} --version '~> {{1.0}}'`
 
 - Update a gem:
 
-`gem update {{gemname}}`
+`gem update {{gem_name}}`
 
 - List all local gems:
 
@@ -29,8 +29,8 @@
 
 - Uninstall a gem:
 
-`gem uninstall {{gemname}}`
+`gem uninstall {{gem_name}}`
 
-- Uninstall specific version of a gem:
+- Uninstall a specific version of a gem:
 
-`gem uninstall {{gemname}} --version {{1.0.0}}`
+`gem uninstall {{gem_name}} --version {{1.0.0}}`

pages/common/irb.md

@@ -0,0 +1,9 @@
+# irb
+
+> Interactive Ruby shell.
+> Evaluate Ruby code read from `stdin`.
+> More information: <https://docs.ruby-lang.org/en/master/IRB.html>.
+
+- Start the interactive shell:
+
+`irb`

pages/common/rake.md

@@ -0,0 +1,25 @@
+# rake
+
+> A Make-like program for Ruby.
+> Tasks for `rake` are specified in a Rakefile.
+> More information: <https://ruby.github.io/rake>.
+
+- Run the `default` Rakefile task:
+
+`rake`
+
+- Run a specific task:
+
+`rake {{task}}`
+
+- Execute `n` jobs at a time in parallel (number of CPU cores + 4 by default):
+
+`rake --jobs {{n}}`
+
+- Use a specific Rakefile:
+
+`rake --rakefile {{path/to/Rakefile}}`
+
+- Execute `rake` from another directory:
+
+`rake --directory {{path/to/directory}}`

pages/common/ruby.md

@@ -1,12 +1,9 @@
 # ruby
 
 > Ruby programming language interpreter.
+> See also: `gem`, `bundler`, `rake`, `irb`.
 > More information: <https://www.ruby-lang.org>.
 
-- Start a REPL (interactive shell):
-
-`irb`
-
 - Execute a Ruby script:
 
 `ruby {{script.rb}}`