ps
(="print status" or "process status") Display the list of currently running
processes with their process ID (PID) numbers. Use ps axu to see
all processes currently running on your system (also those of other users
or without a controlling terminal), each with the name of the owner. Use
"top" to keep listing the processes currently running.
any_command
&
Run any command in the background (the symbol "&" means "run the preceding
command in the background"). The job_number is printed
on the screen so you can bring the command in the foreground (see below)
if you want. I use "&" often when starting a GUI program from an X-terminal.
jobs
List my background or stopped processes and show their job numbers.
fg job_number
Bring a background or stopped process to the foreground.
bg job_number
Place a process in the background, so it is exactly as if it had been
started with &. This will restart a stopped background process. The
current foreground process can often be stopped with z.
If you have stopped or background jobs, you have to type exit
twice in row to log out.
batch
at>updatedbd
Run any command (usually one that is going to take more time to complete)
when the system load is low. I can logout, and the process will
keep running. When the command completes, an email will be sent to me
with the output. In the example above, the "at>" represents a prompt,
the command to run is updatedb, and the
terminates my input to batch (I could start many commands to run, separated
by ).
at 17:00
Execute a command at a specified time. You will be prompted for
the command(s) to run, until you press d. The associated
commands are atq (display the queue of processes started with
at) and atrm (remove a process from the "at queue").
kill
PID
Force a process shutdown. First determine the PID of the process to kill
using ps.
killall
program_name
Kill program(s) by name. For example, killall pppd will
disconnect your dialup network.
nohup
program_name
(=no hungup). Run program_name so that it does not terminate
when you log out. Output is redirected to the file nohup.out
in your home directory. You surely do not want to run an interactive
program under nohup.
xkill
(in X terminal) Kill a GUI-based program with mouse. (Point with your
mouse cursor at the window of the process you want to kill and click.)
kpm
(in X terminal) KDE process manager.
lpc
(as root) Check and control the printer(s). Type "?" to see the list of
available commands.
lpq
Show the content of the printer queue. Under KDE (X-Windows), you may
use GUI-based "Printer Queue" available from "K"menu-Utilities.
lprm
job_number
Remove a printing job "job_number" from the queue.
nice
program_name
Run program_name adjusting its priority. Since the priority is
not specified in this example, it will be increased by 10 (the process
will run slower), from the default value (usually 0). The lower the number
(of "niceness" to other users on the system), the higher the priority.
The priority value may be in the range -20 to 19. Only root may
specify negative values. Use top to display the priorities of
the running processes.
renice
-18 PID
(as root) Change the priority of a running process to minus 18. Normal
users can only adjust processes they own, and only up from the current
value (make them run slower). One could also renice +10 -u peter
to make user peter use fewer cpu clicks so that other user don't suffer
when he runs his computing-intensive tasks.
c,
z, s, and q
also belong to this chapter but they were described previously.
In short they mean: stop the current command, send the current command
to the background, stop the data transfer, resume the data transfer.
lsof
List the opened files. If I am a root, all files will be listed. I can
limit myself to files opened by processes owned by the first console if
I use lsof /dev/tty1 . To list only network files (useful
for a security audit), I would do lsof -i (as root).
watch
-n 60 my_command
Execute my_command repeatedly at 60-second intervals (the
default interval is 2 seconds).
Next > 5.12 Some administration
commands
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