Pass variables to Ruby script via command line

Question

I ve installed RubyInstaller on Windows and I m running IMAP Sync but I need to use it to sync hundreds of accounts  If I could pass these variables to it via command line I could automate the whole process better     Source server connection info  SOURCE NAME    username example com  SOURCE HOST    mail example com  SOURCE PORT   143 SOURCE SSL    false SOURCE USER    username  SOURCE PASS    password     Destination server connection info  DEST NAME    username gmail com  DEST HOST    imap gmail com  DEST PORT   993 DEST SSL    true DEST USER    username gmail com  DEST PASS    password

User · Answer

Don t reinvent the wheel  check out Ruby s way-cool OptionParser library   It offers parsing of flags switches  parameters with optional or required values  can parse lists of parameters into a single option and can generate your help for you   Also  if any of your information being passed in is pretty static  that doesn t change between runs  put it into a YAML file that gets parsed  That way you can have things that change every time on the command-line  and things that change occasionally configured outside your code  That separation of data and code is nice for maintenance   Here are some samples to play with   require  optparse  require  yaml   options      OptionParser new do  opts    opts banner    Usage  example rb  options      opts on  -n    --sourcename NAME    Source name      v  options  source name    v     opts on  -h    --sourcehost HOST    Source host      v  options  source host    v     opts on  -p    --sourceport PORT    Source port      v  options  source port    v    end parse   dest options   YAML load file  destination config yaml   puts dest options  dest name     This is a sample YAML file if your destinations are pretty static   ---  dest name  username gmail com dest host  imap gmail com dest port  993 dest ssl  true dest user  username gmail com dest pass  password   This will let you easily generate a YAML file   require  yaml   yaml        dest name    gt   username gmail com      dest host    gt   imap gmail com      dest port    gt  993     dest ssl     gt  true     dest user    gt   username gmail com      dest pass    gt   password     puts YAML dump yaml

User · Answer

Unfortunately  Ruby does not support such passing mechanism as e g  AWK    gt  awk -v a 1  BEGIN  print a    gt  1   It means you cannot pass named values into your script directly   Using cmd options may help    gt  ruby script rb val 0 val 1 val 2    script rb puts ARGV 0      gt  val 0 puts ARGV 1      gt  val 1 puts ARGV 2      gt  val 2   Ruby stores all cmd arguments in the ARGV array  the scriptname itself can be captured using the  PROGRAM NAME variable   The obvious disadvantage is that you depend on the order of values   If you need only Boolean switches use the option -s of the Ruby interpreter    gt  ruby -s -e  puts  So do I   if  agreed  -- -agreed  gt  So do I    Please note the -- switch  otherwise Ruby will complain about a nonexistent option -agreed  so pass it as a switch to your cmd invokation  You don t need it in the following case    gt  ruby -s script with switches rb -agreed  gt  So do I    The disadvantage is that you mess with global variables and have only logical true false values   You can access values from environment variables    gt  FIRST NAME  Andy Warhol  ruby -e  puts ENV  FIRST NAME     gt  Andy Warhol   Drawbacks are present here to  you have to set all the variables before the script invocation  only for your ruby process  or to export them  shells like BASH     gt  export FIRST NAME  Andy Warhol   gt  ruby -e  puts ENV  FIRST NAME      In the latter case  your data will be readable for everybody in the same shell session and for all subprocesses  which can be a serious security implication   And at least you can implement an option parser using getoptlong and optparse   Happy hacking

User · Answer

You can also try out cliqr  Its pretty new and in active development  But there are stable releases ready to be used  Here is the git repo  https   github com anshulverma cliqr  Look into the example folder to get an idea on how it can be used

User · Answer

tl dr  I know this is old  but getoptlong wasn t mentioned here and it s probably the best way to parse command line arguments today     Parsing command line arguments  I strongly recommend getoptlong  It s pretty easy to use and works like a charm  Here is an example extracted from the link above  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  lt  lt -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   You can call it like this ruby hello rb -n 6 --name --  tmp  What OP is trying to do  In this case I think the best option is to use YAML files as suggested in this answer

User · Answer

Something like this   ARGV each do a    puts  Argument    a   end   then      test rb  test1 test2    or  v1   ARGV 0  v2   ARGV 1  puts v1        prints test1 puts v2        prints test2

User · Answer

You should try console runner gem  This gem makes your pure Ruby code executable from command-line  All you need is to add YARD annotations to your code      runnable This tool can talk to you  Run it when you are lonely      Written in Ruby    class MyClass      def initialize        hello msg    Hello          bye msg    Good Bye       end         runnable Say  Hello  to you         param  String  name Your name        param  Hash  options options        option options  Boolean   second meet Have you met before         option options  String   prefix Your custom prefix     def say hello name  options             second meet   nil       second meet    Nice to see you again   if options  second meet         prefix   options  prefix         message    hello msg              message       prefix    if prefix       message       name           message    second meet if second meet       puts message     end  end   Then run it from console     c run  projects example my class rb  say hello -n John --second-meet --prefix Mr   - gt  Hello  Mr  John  Nice to see you again

User · Answer

Run this code on the command line and enter the value of N   N    gets  1 step N to i  1     i  print  hello world n

User · Answer

Unless it is the most trivial case  there is only one sane way to use command line options in Ruby  It is called docopt and documented here    What is amazing with it  is it s simplicity  All you have to do  is specify the  help  text for your command  What you write there will then be auto-parsed by the standalone     ruby library    From the example      usr bin env ruby require  docopt rb   doc    lt  lt DOCOPT Usage      FILE    --help            FILE    -v               FILE    go  go             FILE     --path  lt path gt                 FILE     lt file gt   lt file gt   Try      FILE    -vvvvvvvvvv          FILE    go go          FILE    --path   here --path   there          FILE    this txt that txt  DOCOPT  begin   require  pp    pp Docopt  docopt doc  rescue Docopt  Exit   gt  e   puts e message end   The output       counted example rb -h Usage    counted example rb --help          counted example rb -v             counted example rb go  go           counted example rb  --path  lt path gt               counted example rb  lt file gt   lt file gt   Try    counted example rb -vvvvvvvvvv        counted example rb go go        counted example rb --path   here --path   there        counted example rb this txt that txt      counted example rb something else   --help   gt false    -v   gt 0    go   gt 0    --path   gt        lt file gt    gt   something    else         counted example rb -v   --help   gt false   -v   gt 1   go   gt 0   --path   gt       lt file gt    gt          counted example rb go go   --help   gt false   -v   gt 0   go   gt 2   --path   gt       lt file gt    gt       Enjoy

[ruby] Pass variables to Ruby script via command line

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