Foreground and Background Processes Management
To illustrate, here’s a directory listing:
user@example:~/scripts/trunk/backup_scripts# ls -l
total 76
-rwxr-xr-x 1 user user 894 2011-06-27 10:00 backup.hwaddr.sh
-rwxr-xr-x 1 user user 12175 2011-05-02 22:54 backup.local.sh
-rwxr-xr-x 1 user user 6194 2011-04-12 16:53 backup.mysql.sh
-rwxr-xr-x 1 user user 14638 2011-04-28 11:29 backup.network.sh
-rwxr-xr-x 1 user user 3201 2011-05-02 09:06 backup.opendirectory.sh
-rwxr-xr-x 1 user user 7871 2011-04-28 11:32 backup.rotate.sh
-rwxr-xr-x 1 user user 3743 2011-04-12 16:53 backup.rpms.sh
-rwx------ 1 user user 5037 2011-06-28 15:03 backup.sh
-rwxr-xr-x 1 user user 4184 2011-06-27 10:01 backup.staging.sh
-rwxr-xr-x 1 user user 3128 2011-06-27 10:58 backup.subversion.sh
Let’s say I started editing a file (e.g. vim backup.sh. I now hit Ctrl+z to ‘push’ the process into the background. This is what I see:
[1]+ Stopped vim backup.sh
user@support:~/scripts/trunk/backup_scripts#
Now I edit another file (or start another process) and hit Ctrl+z again:
[2]+ Stopped vim backup.subversion.sh
user@support:~/scripts/trunk/backup_scripts#
And so on. To list all my background jobs, I can either issue ps or (better) jobs:
user@support:~/scripts/trunk/backup_scripts# ps
PID TTY TIME CMD
3561 pts/0 00:00:00 bash
3697 pts/0 00:00:00 vim
3728 pts/0 00:00:00 vim
3773 pts/0 00:00:00 vim
3790 pts/0 00:00:00 top
3797 pts/0 00:00:00 ps
user@support:~/scripts/trunk/backup_scripts# jobs
[1] Stopped vim backup.sh
[2]+ Stopped vim backup.subversion.sh
[3] Stopped vim backup.network.sh
[4]- Stopped top
The “+” and “-” signs indicate the first and second most recent jobs respectively. Typing fg will bring the job tagged with a “+” into the foreground. From the output above, let’s say you wanted to bring top into the foreground instead:
user@support:~/scripts/trunk/backup_scripts# fg 4
To keep top running in the background for example (“amping off”), you would just type bg 4