Comments on: 6 Ways to Run Shell Commands in Ruby

By: Ilya

Ilya — Wed, 14 Mar 2007 08:58:00 +0000

Thank you! Nice review.

By: Wayne E. Seguin

Wayne E. Seguin — Thu, 05 Jul 2007 22:07:23 +0000

Don’t forget the %x{whoami} which is the delimited form of the backquote `whoami`.

By: Marius

Marius — Fri, 07 Sep 2007 11:11:37 +0000

Hey! Thanks for the overview! Do you happen to know how I can pass a ruby variable to the shell command that needs to be executed? Something like this:

filename = ‘test.tar’ result = `tar xfv` + filename

Of course this does not work, but how do I make it work ? I have been googling for 30 minutes now and I can’t find anything. Greetings from Bonn (DE)

By: Michael

Michael — Sat, 15 Sep 2007 00:18:40 +0000

Marius - you can use

exit_code = system(”tar xfv #{filename}”)

Make sure to use double quotes, not single quotes.

If you need to capture output, use Open3.popen with the same double-quoted string.

By: Jason Campbell

Jason Campbell — Sat, 22 Sep 2007 07:50:30 +0000

Thanks! Seriously. I found this after almost an hour of scouring google. This is just what I needed!

I added a line to Simon Gate’s Basecamp post-commit hook to automatically update a working copy of my repository using the backtick method. I saw the method before but since I am a noob to ruby I didn’t quite get it until I found your article. Thanks again!

By: Floyd

Floyd — Fri, 28 Sep 2007 02:41:58 +0000

Nice summary. It was helpful.

By: Garrett Smith

Garrett Smith — Thu, 18 Oct 2007 17:46:13 +0000

Good write-up, but you forgot to mention that a few of these methods don’t work on certian OSes, such as Windows.

By: james

james — Sun, 21 Oct 2007 11:45:51 +0000

Very useful - Answered a lot of key questions

By: JeanW

JeanW — Thu, 14 Feb 2008 20:12:30 +0000

Great article! We actually ended up going with a simple solution to get our stderr on Windows– we just redirected stderr to stdout inside the backticsk, e.g.

`#{command} #{args} 2>&1`

No need to install a new gem on every machine!

By: Murilo

Murilo — Thu, 28 Feb 2008 01:54:52 +0000

Good tutorial. You just forgot to metion that I need to do require “open3″ at the beginning of Section “Open3″; you only did it at the third block of code. I also couldn’t use open4 on Debian, even after doing gem instal open4, does someone know the reason? (I don’t have any experience on Ruby programming, just found the article and tried it out)

By: links for 2008-03-11 « Bloggitation

links for 2008-03-11 « Bloggitation — Tue, 11 Mar 2008 00:19:22 +0000

[…] 6 Ways to Run Shell Commands in Ruby (tags: ruby programming) […]

By: IceskYsl

IceskYsl — Tue, 08 Apr 2008 15:27:47 +0000

I notice a error like this:

Code: logger.info(”rar a #{local_dir_name} #{local_dir_name}”) oo= %x{rar a #{local_dir_name} #{local_dir_name}} logger.info(”oo=#{oo}”)

Output: rar a 1207666290_2 1207666290_2 oo= Program aborted

can anybody give me a hand?

By: IceskYsl

IceskYsl — Tue, 08 Apr 2008 15:30:29 +0000

and in my localhost,it’s ok,output like this:

Evaluation copy. Please register.

Creating archive 1207667932_2.rar

Adding 1207667932_2/datas.csv OK Adding 1207667932_2/images OK Adding 1207667932_2 OK Done ——–

By: Max

Max — Fri, 11 Apr 2008 16:13:29 +0000

I’m trying to do what Marius is doing, but executing “tainted” input instead. Does anyone know if there is a way to escape shell arguments so they’re safe?

Also, you can install the win32-open3 gem to get this to work on Windows, btw.

Oh, and nice article

By: daniel rails

daniel rails — Mon, 14 Apr 2008 07:59:49 +0000

Hey Nate, thanks for article, this was exactly what I was searching for! Greets, Daniel

By: kingtutt

kingtutt — Sun, 20 Apr 2008 12:38:07 +0000

You’ve restored my faith! And inspired me to use ruby for in place of bash scripting for system administration tasks…and that’s just awesome.

By: wdso

wdso — Thu, 24 Jul 2008 23:12:06 +0000

Brilliant summary. One question though… what about threads?

By: Ben

Ben — Sat, 27 Dec 2008 21:39:01 +0000

Note that Process::Status#to_i doesn’t actually give you the exit status (rather, it gives you _all_ the bits). According to the RDoc

“Posix systems record information on processes using a 16-bit integer. The lower bits record the process status (stopped, exited, signaled) and the upper bits possibly contain additional information (for example the program‘s return code in the case of exited processes)”

If you want the exit status, you need to use Process::Status#exitstatus. To see the problem, note that the exit status of ‘false’ on is 1 (you can see this in the shell). But calling status.to_i gives you 256, not 1. However, calling status.exitstatus give you 1, as expected.

By: Ruby Shell Skripte

Ruby Shell Skripte — Sat, 31 Jan 2009 11:16:39 +0000

[…] Ruby macht es einem dabei sehr einfach externe Skripte und Programme auszuführen. Es gibt allerdings verschiedene Möglichkeiten die in diesem Artikel beschrieben sind: 6 Ways to Run Shell Commands in Ruby […]

By: Aladdin With A Lamp » 『Ruby on Rails』|很好很好的资料！

Aladdin With A Lamp » 『Ruby on Rails』|很好很好的资料！ — Thu, 12 Feb 2009 16:50:06 +0000

[…] 6 Ways to Run Shell Commands in Ruby […]

By: Andrew Grimm

Andrew Grimm — Mon, 06 Apr 2009 07:11:55 +0000

I was trying to work out how to execute a command, get the exit status and ignore the textual output (for an integration test of my code), and the $? after backticks worked for me. Thanks!

By: Inoe

Inoe — Fri, 10 Apr 2009 04:23:37 +0000

thanks its very usefull…. nice post..

By: Les liens du 24 04 2008 au 25 04 2008

Les liens du 24 04 2008 au 25 04 2008 — Fri, 10 Apr 2009 20:32:12 +0000

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By: mz2guild's me2DAY

mz2guild's me2DAY — Tue, 28 Apr 2009 10:55:40 +0000

mz2guild의 생각…

6 Ways to Run Shell Commands in Ruby…

By: emil tin

emil tin — Mon, 18 May 2009 10:45:27 +0000

in ruby 1.9, open3 provides a way to get the exit status. http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/22888

By: links for 2009-12-22 « sySolution

links for 2009-12-22 « sySolution — Tue, 22 Dec 2009 15:01:28 +0000

[…] Pasadena.rb» Blog Archive » 6 Ways to Run Shell Commands in Ruby (tags: shell ruby rubyonrails) […]

By: myself

myself — Wed, 06 Jan 2010 18:19:02 +0000

great! precise , clear and helpful explanation