How to remove new of line in ruby variable created from system script

Question

I used chef for automation.

In one of my scenarios I need to extract a version number of passenger from rvm installed in my system.

I used 'pasver' variable for this:

pasver = `/usr/local/rvm/bin/gem list | grep passenger`.sub /.*\((.*)\).*/, '\1'

But If I use this variable, in this case:

if ! ::File.exists?("/usr/local/rvm/gems/#{node['redmine']['rubyversion']}/gems/passenger-#{pasver}/buildout/apache2/mod_passenger.so") then

Then this condition is always false, and code in if block does not run.

This is because pasver variable contains new of line.

How I can remove this new of line ?

I used next way, but without successfully:

pasver = `/usr/local/rvm/bin/gem list | grep passenger`.sub /.*\((.*)\).*/, '\1'.gsub("\n",'')

Please, mark a relevant answer if you found one. – CodeGroover Oct 05 '13 at 09:42 — CodeGroover, Oct 05 '13 at 09:42
I mark my answer - last answer in this question. – vskubriev Oct 09 '13 at 11:25 — vskubriev, Oct 09 '13 at 11:25

score 2 · Answer 1 · answered Oct 04 '13 at 11:23

2

Why not use

pasver.chomp!

after the system call or,

if ! ::File.exists?("/usr/local/rvm/gems/#{node['redmine']['rubyversion']}/gems/passenger-#{pasver.chomp}/buildout/apache2/mod_passenger.so") then

answered Oct 04 '13 at 11:23

AGS

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This did not help! Because of chef features may be. – vskubriev Oct 04 '13 at 11:36
I Use similar syntax in ERB template, but You recipe did not it. See my code in other file: <% pasver = `/usr/local/rvm/bin/gem list | grep passenger`.sub /.*\((.*)\).*/, '\1'.chomp %> PassengerRoot <%= "/usr/local/rvm/gems/#{node['redmine']`['rubyversion']}/gems/passenger-#{pasver.chomp!}" %> PassengerDefaultRuby /usr/local/rvm/wrappers/<%= node['redmine']`['rubyversion']%>/ruby – vskubriev Oct 04 '13 at 11:38
I would guess the problem is *not* `chomp`, itself, but something else in your implementation. – AGS Oct 04 '13 at 19:05

CodeGroover · Answer 2 · 2013-10-04T13:43:33.147

1

How about this:

irb> require 'rubygems'
irb> g = Gem::Specification.find_all_by_name 'passenger'
irb> g.first.version.version
=> "4.0.19"

edited Oct 04 '13 at 13:43

answered Oct 04 '13 at 13:34

CodeGroover

2,157
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score 0 · Answer 3 · answered Oct 04 '13 at 11:23

0

You can use rstrip() on any string to remove trailing whitespace.

answered Oct 04 '13 at 11:23

score 0 · Accepted Answer · answered Oct 08 '13 at 07:56

Chef-users mailing list suggested to me a solution for regexp

pasver = /usr/local/rvm/bin/gem list | grep passenger.sub /.((.)).*/m, '\1'
But It is not all, there was a problem with using this code in erb template itself. Variable value disappears, but I don'k know why.

For example this code isn't worked.

 <% pasver = `/usr/local/rvm/bin/gem list | grep passenger`.sub /.*\((.*)\).*/, '\1'.chomp %>
    PassengerRoot <%= "/usr/local/rvm/gems/#{node['redmine']['rubyversion']}/gems/passenger-#{pasver.chomp!}" %>
    PassengerDefaultRuby /usr/local/rvm/wrappers/<%= node['redmine']['rubyversion']%>/ruby

This file generates:

    LoadModule passenger_module /usr/local/rvm/gems/ruby-2.0.0-p247/gems/passenger-4.0.19
    /buildout/apache2/mod_passenger.so

I don't get strange behaviour in IRB never. But chef runtime is something else.

My solution is using variables in recipe and then pass it to template resource:

template ".." do
variables ({
:pasver => pasver
})
end

How to remove new of line in ruby variable created from system script

4 Answers4