Running some parts of a script as an unprivileged user with shell environment

Question

I am creating an instance configuration script that sets up a machine.

I am running the script via sudo i.e. sudo run.sh. Most of the steps require root access but some of the script's steps do no require root access and I prefer running them as the unprivileged user who ran the sudo.

Inside the script running with sudo, I am trying to do

sudo -i -u username sh -c 'echo $MY_ENV'

Since .bashrc contains export MY_ENV=something I expect the above command to print "something"

How can I temporarily switch inside the script to the other user to run commands that include the user's shell env ?

possible duplicate of [su options - running command as another user](http://unix.stackexchange.com/questions/1087/su-options-running-command-as-another-user) — jasonwryan, Apr 11 '15 at 07:46
@jasonwryan I've seen that but it says nothing about including the user's env vars as well — Michael, Apr 11 '15 at 07:48
@jasonwryan - This isn't about `sudo` or `su`, I think. Michael - when you call `sh` you don't get `bashrc` doing anything - even if `sh` is a link to `bash`. You can do `ENV=~/.bashrc sh -c 'cmd'` though, maybe. A possible issue with *that* though *is* `sudo`. You can do `sudo env - ENV=~/.bashrc sh -c 'cmd`. Though I'm not positive if it will correctly work with `-c` - have to check that. Oh. jasonwryan - maybe it is about `sudo` after rereading the question. I guess we're talking about `.bashrc` influencing the command before it is run, not a shell's init file. — mikeserv, Apr 11 '15 at 10:51
@Cyrus tried any combination of that, couldn't get it to work, still would not print what's in the `.bashrc` file — Michael, Apr 11 '15 at 19:17

score 2 · Accepted Answer · edited Apr 13 '17 at 12:37

.bashrc is executed only by interactive shells, not by scripts¹. It's the wrong place to define environment variables. See Is there a ".bashrc" equivalent file read by all shells? and the Ubuntu wiki.

You can tell bash to read .bashrc explicitly. Of course you'll have to execute bash, not sh which could be a different shell:

sudo -i -u username bash -c '. `~/.bashrc; echo "$MY_ENV"'

But it's a bad idea because .bashrc files are likely to contain things that assume that they're executed on a terminal and that spend time setting up key bindings, aliases, prompts, etc.

The sane solution is to put environment variable definitions where they belong, in ~/.profile or ~/.pam_environment.

¹ _{Except when bash is called by sshd for some weird reason.}

Running some parts of a script as an unprivileged user with shell environment

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