Using csh & tcsh

Other Applications of Job Control

This section describes other ways in which job control is useful.

Controlling Background Job Output

Putting a command in the background is handy when you want to do other things while the job is running, but the command may write output to the terminal at inconvenient times. If you are editing a file or composing a mail message, you may not want a background job to splatter output all over the screen. Or, if you have multiple background jobs, their output streams may interfere with each other. To avoid these problems, you can use the following command to force background jobs to stop when they are ready to write to the terminal:

% stty tostop

When you're ready to see the output of a background job that is stopped waiting to write, bring the job to the foreground.

To let background jobs write to the terminal at any time, use the following command:

% stty -tostop

The following command sequence illustrates the difference between stty tostop and stty –tostop:

% stty tostop                             Turn tostop on
% date &                                  Run command in the background
[1] 24980                                 Shell reports the job number and the process ID
[1] + Suspended (tty output) date         Job stops when ready to produce output
% fg                                      Bring the job to the foreground
date                                      Shell echoes command line
Mon Sep 12 11:59:14 CDT 1994              Job writes output
% stty -tostop                            Turn tostop off
% date &                                  Run the command in the background
[1] 24982                                 Shell prints the job number and the process ID
Mon Sep 12 11:59:21 CDT 1994              Job writes output without stopping ...