Cron jobs are typically run with a minimal shell (/bin/sh, not
/bin/bash), and tilde expansion is not always performed in such
commands. You may want to use explicit paths, because the PATH
is usually quite short and doesn't include anything set by your
shell's startup scripts (.profile, .bashrc, etc). If
you've installed buildbot (or other python libraries) to an unusual
location, you may need to add a PYTHONPATH specification (note
that python will do tilde-expansion on PYTHONPATH elements by
itself). Sometimes it is safer to fully-specify everything:
@reboot PYTHONPATH=~/lib/python /usr/local/bin/buildbot start /usr/home/buildbot/basedir
Take the time to get the @reboot job set up. Otherwise, things will work fine for a while, but the first power outage or system reboot you have will stop the buildslave with nothing but the cries of sorrowful developers to remind you that it has gone away.