Change user and load entire environment in shell script

Question

I'm having some trouble with an upstart script of ours that changes user and starts up a few ruby daemon processes.

In the past i would simply bash -c "do the business" -l someuser making sure to use the -l flag to emulate a login.

This has worked great until now, our ruby process has been throwing the following error: require: no such file to load -- rubygems (LoadError) after some investigation I found this error only occurs when I run the script as the root user, i.e. (when I sudo su or when being run by upstart).

I think this is a PATH issue as when I manually set the path first it resolves the issue.

Is there a way to change user and load the entire environment?

I have also tried su user -c and sudo.

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To make it easier to test I'm "rooting up" (sudo su) and running which bundle (bundle is a ruby thing).

Here's what I get:

• sudo -i -u webuser which bundle # => no output
• su -l webuser -c which bundle # => no output
• sudo su - webuser -c which bundle # => no output

But ssh'd in as webuser

• which bundle # => /opt/ruby/bin/bundle

Answer 1

Using sudo su - user -c will make it as though you logged in as that person inheriting their path. That's why su user is different from su - user.

However if you are setting the path in a .bashrc file it will only take effect for interactive sessions (i.e. ssh-ing in as that user).

You should instead use .bash_profile or /etc/profile, see this.

Answer 2

For the login context use either:

• sudo -i -u USER COMMAND
• su -l USER -c COMMAND