feat: latest.rb can return just the version num

util/latest.rb

@@ -1,15 +1,19 @@
 #!/usr/bin/env ruby
 
-unless ARGV.length == 2
-  $stderr.puts """USAGE: #{$0} [SUBDIRECTORY] [CONFIG_BASENAME]
-  - obtain the latest version of the config file with basename [CONFIG] from 
+if ARGV.length < 2
+  $stderr.puts """USAGE: #{$0} [SUBDIRECTORY] [CONFIG_BASENAME] [OUTPUT]
+  - obtain the latest version of the config file with basename [CONFIG] from
     [SUBDIRECTORY], assuming [SUBDIRECTORY] contains subdirectories of tag names
   - tag names that are not semantic version numbers, such as `dev`, are ignored
+  - [OUTPUT] may be either:
+    'file':     return the file name (default behavior)
+    'version':  return just the version number
   """
   exit 2
 end
 
-subdir, config = ARGV
+subdir, config = ARGV[0..1]
+output = ARGV.length >= 3 ? ARGV[2] : 'file'
 unless Dir.exist? subdir
   $stderr.puts "ERROR: subdirectory '#{subdir}' does not exist"
   exit 1
@@ -48,4 +52,12 @@
 end
 
 # return the latest version of that config file
-puts configFiles.first
+case output
+when 'file'
+  puts configFiles.first
+when 'version'
+  puts tagdirs.first
+else
+  $stderr.puts "ERROR: unknown [OUTPUT] '#{output}'"
+  exit 1
+end