How to run a cronjob in my regular environment?

Question

Both the shell and environment variables that cronjobs are run in is completely different from the ones presented to me in gnome-terminal. How can I run a cronjob under the same circumstances as if I had run it in the terminal?

My current solution is running the cronjob env DISPLAY=:0.0 gnome-terminal -e my-command, but this pops up a gnome-terminal, which isn't really acceptable.

Answer 1

You can either explicitly specify the environment variables you want at the top of your crontab, or you can source your environment from somewhere.

To add environment variables explicitly, you can use a line like this at the top of your script (after the hashbang):

FOO=bar

To source them from a file, use a line like this:

. /foo/bar/baz

In response to your edit of your question to include gpg-agent, you should be able to source ~/.gpg-agent-info to get $GPG_AGENT_INFO. If it does not exist, try starting gpg-agent with --write-env-file "${HOME}/.gpg-agent-info".

Answer 2

You are correct that processes should not be able to peek in on other process environments. This is very much by design. But, export will neatly package your environment to be picked up by something else.

What you can do is something like this in your .bashrc:

[[ $DISPLAY ]] && export > ~/.cron_bread_crumbs/gonme_env

Then have your cron job simply pick it up.

. /home/user/.cron_bread_crumbs/gnome_env

The file will be full of lines like this:

declare -x ENV_VARIABLE="value"

Values will, of course, be quoted. That's what I meant by saying 'packaged neatly'.

Sourcing this (thereby calling declare -x which is an export) means all subsequent processes that start (and perhaps detach) from the parent cron will also inherit these values.

This is a little kludgy, though, because it assumes that you've popped open one gnome terminal causing the values to be refreshed prior to the cron running. A little sanity in the cron job shouldn't be too difficult to add, however.

Your other option is to start something in the background that just blocks while dumping the environment to a named pipe, then let the cron job pick it up from there. Either way, the kludge lies in making sure something happens via Gnome terminal so the cron job gets the variables.