need to set environment var for a back-ticks command

Question

how to pass an environment variable to a shell command that I execute using Kernel#system et al?

say, I want to run

%x{git checkout -f}

but this command relies on the environment variable $GIT_WORK_TREE. how do I set it?

Answer 1

You should be able to set the variable in Ruby's ENV hash prior to calling the sub-shell:

ENV['GIT_WORK_TREE'] = 'foo'
`echo $GIT_WORK_TREE`

should return "foo".

See the ENV[]= documentation for more information.

---

[1] (pry) main: 0> ENV['GIT_WORK_TREE'] = 'foo'
"foo"
[2] (pry) main: 0> `echo $GIT_WORK_TREE`
"foo\n"

Answer 2

You can use Process.spawn to set the environment:

spawn({'GIT_WORK_TREE' => '/foo/bar'}, "git checkout -f")