See the UNIX Programmers Manual or via % man csh
% jobs
produces something like the following:
[1] Stopped cod
[2] - Stopped mail
[3] + Stopped guppy
The [1] specifies job #1, the + specifies the most current job,
the - specifies the previous job, the identifiers on the right specify
the name of the job (not necessarily unique).
To cause any one of these jobs to come back to the foreground, use the
fg command. So,
% fg %2
would cause the mail session to become active again, and
% fg %mail
would also cause the mail session to become active, but if there were
two jobs with the name 'mail' then another more specific form would be
necessary.
To cause a job to fire up in background, use the ampersand, thus:
% nroff -me mtext.l &
To cause an executing job to stop and start up again in background,
first stop it with CTRL-Z, then issue the command:
% bg