Linux fundamental - Chap 08 proc

Chapter 8Chapter 8
Process ManagementProcess Management
Ref. Pge. 85

What is a process?What is a process?
●
A binary commandA binary command
●
Loaded into memoryLoaded into memory
●
Processed by CPUProcessed by CPU
●
Release memory when quitRelease memory when quit
●
Identified by PIDIdentified by PID

Process TreeProcess Tree
●
Every process is generated by parentEvery process is generated by parent
processprocess
●
Child process inherits environmentChild process inherits environment
from it's parentfrom it's parent
●
Child process returns a value to parentChild process returns a value to parent
when exitwhen exit
●
TheThe initinit is the root of process treeis the root of process tree

Process EnvironmentProcess Environment
●
PID/PPIDPID/PPID
●
UID/GIDUID/GID
●
Command NameCommand Name
●
VariablesVariables
●
ParametersParameters
●
File DescriptorsFile Descriptors
●
Data ...Data ...

Process Management UtilitiesProcess Management Utilities
●
pstreepstree
– Shows the whole process treeShows the whole process tree
– Common optionsCommon options
●
pp : with PID: with PID
●
uu : with user name: with user name

●
psps
– Shows process informationShows process information
– Common options (standard style)Common options (standard style)
●
ll : long format: long format
●
ee : every process: every process
– Common options (BSD style)Common options (BSD style)
●
aa : all process related to terminal: all process related to terminal
●
uu : user format: user format
●
xx : current user's process / all process with option: current user's process / all process with option aa
●
ww : whole line information: whole line information
Ref. Pge. 86

●
toptop
– Sorts process in order (default by CPU usage)Sorts process in order (default by CPU usage)
– Common options:Common options:
●
d d nn : delay in: delay in nn seconds intervalseconds interval
●
n n nn : refresh: refresh nn timestimes
●
bb : batch mode in pipe line: batch mode in pipe line
Ref. Pge. 90

Process UtilitiesProcess Utilities
– Common internal commands ofCommon internal commands of toptop::
●
<space> <space> : refresh screen: refresh screen
●
h,?h,? : help: help
●
ss : delay second: delay second
●
rr : renice a process: renice a process
●
kk : kill a process: kill a process
●
F,OF,O : select sorting field: select sorting field
●
ii : toggle idle processes: toggle idle processes
●
qq : quit: quit

●
uptimeuptime
– Displays system running informationDisplays system running information

Job ControlJob Control
●
Foreground JobForeground Job
– Normal way to run a commandNormal way to run a command
– The job occupies the terminal till finishThe job occupies the terminal till finish
– Parent process stay in sleep statusParent process stay in sleep status
– Can be stopped by pressingCan be stopped by pressing ctrlzctrlz
●
Background JobBackground Job
– Ending withEnding with && when running a commandwhen running a command
– The shell prompt occurred for typing nextThe shell prompt occurred for typing next
commandcommand
– Parent process is still runningParent process is still running
Ref. Pge. 92

UsingUsing jobsjobs
●
jobsjobs
– Displays all background jobs in current shellDisplays all background jobs in current shell
– Common options:Common options:
●
ll : display PID: display PID

Job Control SwitchingJob Control Switching
●
fgfg
– Bring a background/stopped job to foregroundBring a background/stopped job to foreground
●
^z^z
– Stop a foreground jobStop a foreground job
●
bgbg
– Put a stopped job to backgroundPut a stopped job to background

foreground
background
stopped
^Z
bg
fg
fg

Process PriorityProcess Priority
●
Processes have different priorities toProcesses have different priorities to
consume the CPU time slices in two ways:consume the CPU time slices in two ways:
– PRI (priority)PRI (priority)
●
Higher value has more CPU timeHigher value has more CPU time
●
Dynamic adjusted by kernelDynamic adjusted by kernel
– NI (nice)NI (nice)
●
Higher value has less CPU timeHigher value has less CPU time
●
Adjusted by user: -20~19Adjusted by user: -20~19
Ref. Pge. 93

UsingUsing nicenice
●
nice [nice [NINI] command_line] command_line
●
nice [n nice [n NINI] command_line] command_line
– Runs command with specifiedRuns command with specified NINI valuevalue
– The default value is 10The default value is 10

UsingUsing renicerenice
●
renice <renice <New_NINew_NI> PID ...> PID ...
– Adjusts the NI value for a process by PIDAdjusts the NI value for a process by PID
– Regular users can only increase NI valueRegular users can only increase NI value
– Regular users can only adjust owning processesRegular users can only adjust owning processes
●
renice <renice <New_NINew_NI> u > u useruser
– Adjusts the NI value for all processes owned byAdjusts the NI value for all processes owned by
specified userspecified user
– Root onlyRoot only

Process SignalProcess Signal
●
Change the status of a running processChange the status of a running process
●
Common signals:Common signals:
No. Name Function
1 HUP reload configuration
2 INT interrupt a process
3 QUIT quit with some actions
9 KILL terminated immediately
15 TERM terminated normally
18 CONT continue a stopped process
19 STP stop a process
Ref. Pge. 94

UsingUsing killkill
●
kill [sig] <%JID/PID> …kill [sig] <%JID/PID> …
– Sends a signal to processes or jobsSends a signal to processes or jobs
– The default signal isThe default signal is TERMTERM
– Signal formats:Signal formats:
●
nn : the signal number: the signal number
●
namename : the signal name: the signal name

UsingUsing killallkillall
●
killall [sig] cmd_name …killall [sig] cmd_name …
– Sends a signal to processes by nameSends a signal to processes by name
– All processes by the command receive the signalAll processes by the command receive the signal
– Regular users can only send signals to owningRegular users can only send signals to owning
processesprocesses

Linux fundamental - Chap 08 proc

More Related Content

What's hot (20)

Viewers also liked (10)

Similar to Linux fundamental - Chap 08 proc (20)

More from Kenny (netman) (14)

Recently uploaded (20)

Linux fundamental - Chap 08 proc