11.6. Stopped Jobs Count

Torben Fjerdingstad (<>) wrote to tell me that he often stops jobs and then forgets about them. He uses his prompt to remind himself of stopped jobs. Apparently this is fairly popular, because as of Bash 2.04, there is a standard escape sequence for jobs managed by the shell:

[giles@zinfandel]$ export PS1='\W[\j]\$ '
giles[0]$ man ls &
[1] 31899
giles[1]$ xman &
[2] 31907

[1]+  Stopped                 man ls
giles[2]$ jobs
[1]+  Stopped                 man ls
[2]-  Running                 xman &
giles[2]$

Note that this shows both stopped and running jobs. At the console, you probably want the complete count, but in an xterm you're probably only interested in the ones that are stopped. To display only these, you could use something like the following:

[giles@zinfandel]$ function stoppedjobs {
-- jobs -s | wc -l | sed -e "s/ //g"
-- }
[giles@zinfandel]$ export PS1='\W[`stoppedjobs`]\$ '
giles[0]$ jobs
giles[0]$ man ls &
[1] 32212

[1]+  Stopped                 man ls
giles[0]$ man X &
[2] 32225

[2]+  Stopped                 man X
giles[2]$ jobs
[1]-  Stopped                 man ls
[2]+  Stopped                 man X
giles[2]$ xman &
[3] 32246
giles[2]$ sleep 300 &
[4] 32255
giles[2]$ jobs
[1]-  Stopped                 man ls
[2]+  Stopped                 man X
[3]   Running                 xman &
[4]   Running                 sleep 300 &

This doesn't always show the stopped job in the prompt that follows immediately after the command is executed - it probably depends on whether the job is launched and put in the background before jobs is run.

There is a known bug in Bash 2.02 that causes the jobs command (a shell builtin) to return nothing to a pipe. If you try the above under Bash 2.02, you will always get a "0" back regardless of how many jobs you have stopped. This problem is fixed in 2.03.

Relative speed: 'jobs -s | wc -l | sed -e "s/ //g" ' takes about 0.24 seconds on an unloaded 486SX25.