Add help command

  - Provide information about usage for each command
  - Update README.md to add commands and correct grammar

README.md

@@ -15,7 +15,7 @@ Supported Systems
 Overview
 --------
 
-Chromebooks with Chrome OS run a linux kernel - the only missing piece to use them as full-featured linux distro was gcc and make with their dependencies. Well, the piece isn't missing anymore. Say hello to chromebrew!
+Chromebooks with Chrome OS run a Linux kernel. The only missing pieces to use them as full-featured Linux distro were gcc and make with their dependencies. Well, these pieces aren't missing anymore. Say hello to chromebrew!
 
 Prerequisites
 -------------
@@ -32,7 +32,7 @@ Open the terminal with Ctrl+Alt+T and type `shell`.
 
 If this command returns `ERROR: unknown command: shell` please have a second look at the prerequisites and make sure your Chromebook is in developer mode.
 
-Then download and run the installation script
+Then download and run the installation script below:
 
     wget -q -O - https://raw.github.com/skycocker/chromebrew/master/install.sh | bash
 
@@ -43,10 +43,15 @@ Usage
 
 Where available commands are:
 
-  * search [looks for a package]
-  * download [downloads a package to `CREW_BREW_DIR` (`/usr/local/tmp/crew` by default), but doesn't install it]
-  * install [installs a package along with its dependencies. You'll be prompted for confirmation]
-  * remove [removes a package.]
+  * build [build a package from source and store the archive and checksum in the current working directory]
+  * download [download a package to `CREW_BREW_DIR` (`/usr/local/tmp/crew` by default), but don't install it]
+  * help [get information about command usage]
+  * install [install a package along with its dependencies after prompting for confirmation]
+  * remove [remove a package]
+  * search [look for a package]
+  * update [update crew itself]
+  * upgrade [update all or a specific package]
+  * whatprovides [regex search for package(s) that contains file(s)]
 
 Available packages are listed in the [packages directory](https://github.com/skycocker/chromebrew/tree/master/packages).
 
@@ -57,6 +62,6 @@ Chromebrew will wipe its `BREW_DIR` (`/usr/local/tmp/crew` by default) after ins
 License
 -------
 
-Copyright 2013 Michal Siwek and [all the awesome contributors](https://github.com/skycocker/chromebrew/graphs/contributors)
+Copyright 2013 Michal Siwek and [all the awesome contributors](https://github.com/skycocker/chromebrew/graphs/contributors).
 
-This project including all of its source files is released under the terms of [GNU General Public License (version 3 or later)](http://www.gnu.org/licenses/gpl.txt)
+This project including all of its source files is released under the terms of [GNU General Public License (version 3 or later)](http://www.gnu.org/licenses/gpl.txt).

crew

@@ -69,6 +69,49 @@ def search (pkgName, silent = false)
   abort "package #{pkgName} not found :("
 end
 
+def help (pkgName)
+  case @pkgName
+  when "build"
+    puts "Build a package."
+    puts "Usage: crew build [package]"
+    puts "Build [package] from source and place the archive and checksum in the current working directory."
+  when "download"
+    puts "Download a package."
+    puts "Usage: crew download [package]"
+    puts "Download [package] to `CREW_BREW_DIR` (`/usr/local/tmp/crew` by default), but don't install it."
+  when "install"
+    puts "Install a package."
+    puts "Usage: crew install [package]"
+    puts "The [package] must be a valid name.  Use `crew search [package]` to search for a package to install."
+  when "remove"
+    puts "Remove a package."
+    puts "Usage: crew remove [package]"
+    puts "The [package] must be currently installed."
+  when "search"
+    puts "Look for a package."
+    puts "Usage: crew search [package]"
+    puts "If [package] is omitted, all packages will be returned.  (i) in front of the name means the package is installed."
+    puts "Tips:"
+    puts "  crew search | grep '(i)' will return all installed packages."
+    puts "  crew search | grep -v '(i)' will return all available packages not already installed."
+  when "update"
+    puts "Update crew."
+    puts "Usage: crew update"
+    puts "This only updates crew itself.  Use 'crew upgrade' to update packages."
+  when "upgrade"
+    puts "Update package(s)."
+    puts "Usage: crew upgrade [package]"
+    puts "If [package] is omitted, all packages will be updated.  Otherwise, a specific package will be updated."
+    puts "Use 'crew update' to update crew itself."
+  when "whatprovides"
+    puts "Determine which package(s) contains file(s)."
+    puts "Usage: crew whatprovides [pattern]"
+    puts "The [pattern] is a search string which can contain regular expressions."
+  else
+    puts "Available commands: build, download, install, remove, search, update, upgrade, whatprovides"
+  end
+end
+
 def whatprovides (pkgName)
   fileArray = []
   Find.find (CREW_CONFIG_PATH + 'meta/') do |packageList|
@@ -521,6 +564,13 @@ def remove (pkgName)
 end
 
 case @command
+when "help"
+  if @pkgName
+    help @pkgName
+  else
+    puts "Usage: crew help [command]"
+    help nil
+  end
 when "search"
   if @pkgName
     search @pkgName
@@ -531,14 +581,14 @@ when "whatprovides"
   if @pkgName
     whatprovides @pkgName
   else
-    puts "Usage: crew whatprovides [pattern]"
+    help @pkgName = "whatprovides"
   end
 when "download"
   if @pkgName
     search @pkgName
     download
   else
-    puts "Usage: crew download [package]"
+    help @pkgName = "download"
   end
 when "update"
   update
@@ -549,26 +599,26 @@ when "install"
     search @pkgName
     resolve_dependencies_and_install
   else
-    puts "Usage: crew install [package]"
+    help @pkgName = "install"
   end
 when "build"
   if @pkgName
     search @pkgName
     resolve_dependencies_and_build
   else
-    puts "Usage: crew build [package]"
+    help @pkgName = "build"
   end
 when "remove"
   if @pkgName
     remove @pkgName
   else
-    puts "Usage: crew remove [package]"
+    help @pkgName = "remove"
   end
 when nil
   puts "Chromebrew, version 0.4.2"
   puts "Usage: crew [command] [package]"
-  puts "Available commands: build, download, install, remove, search, update, upgrade, whatprovides"
+  help nil
 else
   puts "I have no idea how to do #{@command} :("
-  puts "Available commands: build, download, install, remove, search, update, upgrade, whatprovides"
+  help nil
 end