Setting environment variables in .screenrc

Question

I'm trying to write a .screenrc file that I can use to set up for a developing on a particular project - It will start a few screens, cd to the right places, open up the right files in an editor, and set some environment variables needed for testing.

I can't get the environment setup to work.. I've tried putting this in `~/.screenrc:

setenv PATH ~/src/my_proj/bin/:$PATH

This doesn't work, and I think the problem is that after screen sets PATH, the regular shell initialization scripts kick in and change it on me.

I don't want to disable the regular shell init scripts. Is there any way to make screen setenv after the shell is initialized? Or alternatively, can screen set a variable to read-only?

Answer 1

There's no way that screen can change the environment variables of a shell process once that process has launched, nor is there any way to make an environment variable read-only (values are stored in each process's memory, and each process has full access to them).

(Well, there might be some ugly system-specific way to do it, but it's the kind of thing Unix-like systems are designed to keep you from doing.)

You'll need to modify your shell's initialization script so that it retains the existing value of $PATH, possibly adding to it, rather than setting it to some new value ignoring its existing value.

If you want to do this conditionally, you can test for the existence of $STY, which is set only if the shell (or any other process) is running under screen.

Also, screen's setenv command doesn't seem to recognize the ~ character. I tried adding a similar setenv to a temporary screenrc, and $PATH contained a literal ~ character. bash seems to recognize the ~ syntax in $PATH, but other shells do not. Replace the ~ by $HOME, which screen does recognize.

Answer 2

for me the line

setenv PATH /home/someuser/bin:$PATH

in the screenrc file did the trick.

I think the expansion of '~' to '/home/someuser' is bash specific and will not work within the screenrc.