Chef not_if/only_if command result and string comparison

I'm trying to run a command and compared its output but it appears my bellow code isn't working as I would expect it to.

execute 'testcond' do
  command "echo success"
  only_if {"lsb_release -rs" == '22.04'}
end

Solution

The guard you are using relies on the return status of the expression within { }. The expression you have is more like comparing two strings lsb_release -rs and 22.04. This evaluates to false, and as expected the execution is skipped.

I'd recommend using node attribute that Chef collects about the node. Example:

execute 'testcond' do
  command 'echo success'
  only_if { node['platform_version'] == '22.04' }
end

If you would like to use the command, we can get the result of the command in a variable, and then compare it within only_if guard.

distro_ver = `lsb_release -rs`

execute 'testcond' do
  command 'echo success'
  only_if { distro_ver.chomp! == '22.04' }
end

Note that I'd to use chomp as output of the command adds a newline (\n).