PROCESS:
A
process is defined as a program in Execution.Each of the process have
a unique identification number alloted by a kernal.
INTERNAL
AND EXTERNAL COMMANDS:
The
classification of command depending on whether they generate seperate
process or not upon the running.
Commands
that generate seperate processes upon the running are called external
command.
Eg:
cat,who
Command
that do not generate new process
when
they are running are called internal commands.
Eg:
mkdir,rm,cd
7.6 The ps Command
The
ps
(i.e., process
status)
command is used to
provide information about the currently running processes,
including their process
identification numbers
(PIDs).
guest-9e48Yv@uglab:~$
ps
\
PID TTY TIME CMD
28601
pts/3 00:00:00 bash
28652
pts/3 00:00:00 ps
|
TTY is the name of the console or terminal that the user logged into.
PID: Process Identification Number
The -a option tells ps to list the processes of all users on the system rather than just those of the current user
guest-9e48Yv@uglab:~$
ps -a
PID
TTY TIME CMD
28653
pts/3 00:00:00 ps
The
-f option
generates a listing that contains fewer items of information for each
process
guest-9e48Yv@uglab:~$
ps -f
UID
PID PPID C STIME TTY TIME CMD
116
28601 28410 0 15:24 pts/3 00:00:00 bash
116
28654 28601 0 15:25 pts/3 00:00:00 ps -f
The
-e option
generates a list of information about every process currently running
guest-9e48Yv@uglab:~$
ps -e
PID
TTY TIME CMD
27747
? 00:00:00 gnome-session
27795
? 00:00:00 dbus-launch
27796
? 00:00:00 dbus-daemon
27806
? 00:00:00 at-spi-bus-laun
27810
? 00:00:00 dbus-daemon
27813
? 00:00:00 at-spi2-registr
27826
? 00:00:00 dconf-service
27838
? 00:00:00 gconfd-2
27863
? 00:00:00 gnome-settings-
27872
? 00:00:00 pulseaudio
27878
? 00:00:00 gvfsd
27886
? 00:00:15 compiz
27900
? 00:00:00 nm-applet
27901
? 00:00:00 gnome-fallback-
27902
? 00:00:00 polkit-gnome-au
27903
? 00:00:01 nautilus
27916
? 00:00:00 gvfs-udisks2-vo
27928
? 00:00:00 gvfs-gphoto2-vo
27932
? 00:00:00 gvfs-mtp-volume
27938
? 00:00:00 gvfs-afc-volume
27944
? 00:00:00 gvfsd-trash
27951
? 00:00:00 bamfdaemon
27956
? 00:00:00 sh
27957
? 00:00:00 gtk-window-deco
27961
? 00:00:00 unity-panel-ser
27963
? 00:00:00 hud-service
27983
? 00:00:00 indicator-messa
27985
? 00:00:00 indicator-sound
27987
? 00:00:00 indicator-sessi
27989
? 00:00:00 indicator-print
27998
? 00:00:00 indicator-appli
28000
? 00:00:00 indicator-datet
28001
? 00:00:00 indicator-bluet
28002
? 00:00:00 indicator-sync-
28038
? 00:00:00 evolution-sourc
28045
? 00:00:00 gvfsd-burn
28061
? 00:00:00 unity-applicati
28063
? 00:00:00 unity-files-dae
28065
? 00:00:00 unity-lens-frie
28068
? 00:00:00 unity-music-dae
28076
? 00:00:00 unity-lens-phot
28078
? 00:00:00 unity-shopping-
28080
? 00:00:00 unity-video-len
28119
? 00:00:00 zeitgeist-daemo
28135
? 00:00:00 zeitgeist-fts
28137
? 00:00:00 zeitgeist-datah
28139
? 00:00:00 cat
28142
? 00:00:00 sh
28154
? 00:00:00 pxgsettings
28160
? 00:00:00 sh
28161
? 00:00:00 pxgsettings
28166
? 00:00:22 firefox
28171
? 00:00:00 unity-scope-gdr
28173
? 00:00:00 unity-scope-vid
28175
? 00:00:00 unity-musicstor
28205
? 00:00:00 sh
28207
? 00:00:00 pxgsettings
28214
? 00:00:00 unity-webapps-s
28244
? 00:00:00 telepathy-indic
28250
? 00:00:00 mission-control
28259
? 00:00:00 gnome-screensav
28286
? 00:00:00 deja-dup-monito
28325
? 00:00:00 geoclue-master
28329
? 00:00:00 ubuntu-geoip-pr
28332
? 00:00:00 sh
28333
? 00:00:00 pxgsettings
28370
? 00:00:00 gvfsd-http
28388
? 00:00:00 sh
28390
? 00:00:00 pxgsettings
28401
? 00:00:00 gedit
28410
? 00:00:00 gnome-terminal
28416
pts/2 00:00:00 bash
28468
? 00:00:00 oosplash
28524
? 00:00:12 soffice.bin
28601
pts/3 00:00:00 bash
28656
pts/3 00:00:00 ps
The
-u option
tells ps to provide detailed information about each process.
guest-dZiUbS@uglab-OptiPlex-3010:~$
ps -u
USER
PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
136
2468 0.0 0.2 23260 4500 pts/0 Ss 16:19 0:00 bash
136
2855 0.0 0.0 18160 1236 pts/0 R+ 16:29 0:00 ps -u
-t option Select all processes associated with this terminal. Identical
guest-dZiUbS@uglab-OptiPlex-3010:~$
ps -t
PID
TTY STAT TIME COMMAND
2468
pts/0 Ss 0:00 bash
2902
pts/0 R+ 0:00 ps -t
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