# Declare a shell alias in a ruby file **URL:** \ **Category:** Ruby\ **Created:** [September 3, 2009, 5:25pm UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898 "2009-09-03T17:25:44Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![jney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/49beb7/32.png) [@jney](https://www.ruby-forum.com/u/jney)\ **Post date:** [September 3, 2009, 5:25pm UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898/1 "2009-09-03T17:25:44Z")
Hello, I’m trying to declare a shell alias from a ruby file. here is the file test.rb : # begin test.rb `alias world='echo hello'` # end test.rb I’m launching it : > ruby test.rb Then launching the alias : > world > -bash: world: command not found Does anyone know how do i declare a shell alias from a ruby file ? ---
**Author:** ![jney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/49beb7/32.png) [@jney](https://www.ruby-forum.com/u/jney)\ **Post date:** [September 3, 2009, 6:16pm UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898/2 "2009-09-03T18:16:06Z")
At 2009-09-03 11:22AM, “jney” wrote: > Hello, > > I’m trying to declare a shell alias from a ruby file. > > here is the file test.rb : > > # begin test.rb > > `alias world='echo hello'` you spawn a shell, declare the alias, then the shell exits taking the alias with it. > I’m launching it : > > > ruby test.rb > > Then launching the alias : > > > world > > -bash: world: command not found > > Does anyone know how do i declare a shell alias from a ruby file ? If you want a child process to make changes to the current process, you have to make the child tell the parent what to do and then the parent has to do it. #### alias.rb outputs shell commands puts \<\ **Author:** ![jney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/49beb7/32.png) [@jney](https://www.ruby-forum.com/u/jney)\ **Post date:** [September 3, 2009, 6:16pm UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898/3 "2009-09-03T18:16:09Z") Jean-sébastien Jney wrote: > Hello, > > I’m trying to declare a shell alias from a ruby file. > > here is the file test.rb : > > # begin test.rb > > `alias world='echo hello'` > > # end test.rb > > I’m launching it : > > > ruby test.rb > > Then launching the alias : > > > world > > -bash: world: command not found > > Does anyone know how do i declare a shell alias from a ruby file ? You cannot. The processes are started as follows: your shell --------------\> ruby process --------\> another shell ruby test.rb `xxx` Each process is completely independent of the others - with its own address space, and its own copy of the ENVironment. When the second shell terminates, it cannot affect the ruby process, nor the original shell which started that ruby process. The only way you can do this is from the original shell itself. Either type your alias command at the shell prompt, or put it in a file and do . myscript The dot (.) means “read this file and execute it as commands within this shell” You may find the comp.unix.shell FAQ helpful. ---
**Author:** ![jney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/49beb7/32.png) [@jney](https://www.ruby-forum.com/u/jney)\ **Post date:** [September 4, 2009, 12:30pm UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898/4 "2009-09-04T12:30:55Z")
At 2009-09-04 04:32AM, “Jean-Sébastien” wrote: > ruby one, althrough my file is starting by “#!/usr/bin/env ruby”. > Brian is saying that the ruby script writes shell commands to a file > named “myscript” (instead of printing them to stdout). Then the shell > will source that file (instead of ‘eval’-ing its stdin). ---
**Author:** ![jney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/49beb7/32.png) [@jney](https://www.ruby-forum.com/u/jney)\ **Post date:** [September 4, 2009, 10:43am UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898/5 "2009-09-04T10:43:11Z")
On 3 sep, 18:16, Brian C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > I’m launching it : > > The processes are started as follows: > > type your alias command at the shell prompt, or put it in a file and do > > . myscript > > The dot (.) means “read this file and execute it as commands within this > shell” > > ## You may find the comp.unix.shell FAQ helpful. > > Posted viahttp://www.ruby-forum.com/. Thank you both of you. eval $(ruby test.rb) works for me. But output have to a one line command separate by “;”. “. myscript” doesn’t not work for me. It doesn’t read my file as a ruby one, althrough my file is starting by “#!/usr/bin/env ruby”. Thanks. ---
**Author:** ![jney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/49beb7/32.png) [@jney](https://www.ruby-forum.com/u/jney)\ **Post date:** [September 5, 2009, 12:02am UTC](https://www.ruby-forum.com/t/declare-a-shell-alias-in-a-ruby-file/174898/6 "2009-09-05T00:02:58Z")
Glenn, Do you know how to unsubscribe from these e-mails? Thanks, Steve — On Fri, 9/4/09, Glenn J. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: From: Glenn J. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Subject: Re: declare a shell alias in a ruby file To: “ruby-talk ML” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Date: Friday, September 4, 2009, 6:30 AM At 2009-09-04 04:32AM, “Jean-Sébastien” wrote: >  ruby one, althrough my file is starting by “#!/usr/bin/env ruby”. > Brian is saying that the ruby script writes shell commands to a file > named “myscript” (instead of printing them to stdout). Then the shell > will source that file (instead of ‘eval’-ing its stdin).