2016-10-5 Linux Basic Learning-process and job management

Process and Job Management

Uninterruptible sleep: Non-disruptive sleeping
Interruptible sleep: Sleeps can be interrupted

Cow:copy on write when copying

VSZ: Virtual Memory Set
RSS: Resident Memory Set

100-139: Users can control
Nice value: Elegant
-20 ~-19
100 ~ 139
Normal users can only adjust the nice value of the process
Super User Adjustable Height
0-99: Kernel tuning

Under the/proc file, you can see many process numbers
Init: The process number can only be 1, the first process

Large o Standard
O (1)
O (N)
O (LOGN)
O (n^2)
O (2^n)

Classification of processes:
Terminal-related processes
Regardless of the terminal, the process

Process Status:
P: Non-disruptive sleep
R: Run or ready
S: Sleeps can be interrupted
T: Stop
Z: Zombie
B: Blocking

<: high-priority process
N: Low-priority process
+: Processes in the foreground process group
L: Multithreaded Process
S: Session process first Process

[Email protected] ~]#PS aux | head
USER PID%cpu%MEM VSZ RSS TTY STAT START time COMMAND
Root 1 0.0 0.1 2828 1404? Ss 02:27 0:01/sbin/init
Root 2 0.0 0.0 0 0? S 02:27 0:00 [Kthreadd]
Root 3 0.0 0.0 0 0? S 02:27 0:00 [migration/0]
Root 4 0.0 0.0 0 0? S 02:27 0:00 [ksoftirqd/0]
Root 5 0.0 0.0 0 0? S 02:27 0:00 [watchdog/0]
Root 6 0.0 0.0 0 0? S 02:27 0:00 [events/0]
Root 7 0.0 0.0 0 0? S 02:27 0:00 [Cpuset]
Root 8 0.0 0.0 0 0? S 02:27 0:00 [Khelper]
Root 9 0.0 0.0 0 0? S 02:27 0:00 [Netns]

**command Plus [] is the kernel process

PS: Specialized viewing process
Two different styles:
SYSV Style:-
BSD Style:

Common options
A: Show BSD style, display the process related to terminal
U
X: Display is not related to the terminal process

-F: Full style
-E: Show All threads (represents-a)
-L: Long format (pri denotes priority, ni denotes nice value)
-O: Specify properties

[Email protected] ~]# Ps-el | Head
Priority level
F S UID PID PPID C PRI NI ADDR SZ Wchan TTY time CMD
4 S 0 1 0 0 80 0-707-? 00:00:01 Init
1 S 0 2 0 0 80 0-0-? 00:00:00 Kthreadd
1 S 0 3 2 0-40--0-? 00:00:00 migration/0
1 S 0 4 2 0 80 0-0-? 00:00:00 ksoftirqd/0
5 S 0 5 2 0-40--0-? 00:00:00 watchdog/0
1 S 0 6 2 0 80 0-0-? 00:00:00 events/0
1 S 0 7 2 0 80 0-0-? 00:00:00 Cpuset
1 S 0 8 2 0 80 0-0-? 00:00:00 Khelper
1 S 0 9 2 0 80 0-0-? 00:00:00 Netns


!!!!!!!!! Find common uses for a process!!!!!!!
[[Email protected] ~]# PS aux | grep "Bash"
Root 1767 0.0 0.1 7844 1620 tty1 ss+ 02:28 0:00-bash
Root 1790 0.0 0.1 6700 1616 pts/0 Ss 02:29 0:00-bash
Root 2692 0.0 0.0 5936 720 pts/0 d+ 05:35 0:00 grep bash

Pstree: Displays the process tree of the current system

Pgrep: Finding process numbers that match certain characteristics in grep style
-U: Specifies that a user is the owner of a process
eg
[[email protected] ~]# pgrep-u root bash
1767
1790

PIDOF: Find the ID number of its related process according to the program name

Top:
M: Sort based on the size of the resident memory
P: Sort by CPU percent usage
T: Sort by cumulative time

L: Show average load time and start time
T: whether to display process and CPU status related information
m: Whether memory-related information is displayed

C: Whether to display full command line information
Q: Exit Top
K: Terminate a process

Options:
-D #: Specify the time delay, in seconds
-B: Turn screen display, batch mode
-N #: In batch mode, display a total of several times screen

inter-process communication(Ipc:inter Process Communication)
Shared memory
Signal: Signal
Semaphore: Semaphore

Important signals under the kill-l:
1:sighup allows a process to reread its configuration file without restarting, and to have the new configuration information take effect
2:sigint Terminal a process =ctrl+c
9:sigkill kills a process
15:sigterm terminates a process, the default signal

Specify a signal:
Signal Number: Kill-l
Signal Name: Kill-sigkill
Signal name shorthand: Kill-kill

Kill PID: Terminates the specified process number
Kill command: All processes that contain this command will be killed

Adjust nice values
To adjust the nice value of a process that has already started
renice Nice value PID

Specify a nice value at startup:
nice-n NI Command

[Email protected] ~]# PS Axo Pid,nice,command | Head
PID NI COMMAND

7 0 [Cpuset]
8 0 [Khelper]
9 0 [Netns]
[Email protected] ~]# renice 3 8 The nice value of the ———— tuning process with PID 8 is 3
8:old priority 0, new Priority 3
[Email protected] ~]# PS Axo Pid,nice,command | Head
PID NI COMMAND

7 0 [Cpuset]
8 3 [Khelper]
9 0 [Netns]
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Foreground job: Occupy command prompt
Background job: After startup, release the command prompt, and subsequent operations are completed in the background

jobs: View all jobs in the background
Job number: Different from process number
+: Command will default action for jobs
-: command to assign a second default action to the job

Front desk--Backstage:
CTRL + Z to send the front desk work backstage
Command & let commands take place in the background

BG: Keep A background stop job running (in the background)
BG [[%]job-id] Job number

FG: Returning background jobs to the foreground
FG [[%]job-id] Job number

----% can be saved
----If the background process is to be killed, the% cannot be saved
Kill%job-id

Vmstat: System Status View Command
# with a number, specify to refresh every few seconds, dynamic display
# # with two numbers, the first one is displayed every few seconds, the second one is refreshed several times

Uptime
Top the first line of content

cat/proc/meminfo: Memory-related information

cat/proc/# Process Number/maps: Process information

This article is from the "11160930" blog, please be sure to keep this source http://11170930.blog.51cto.com/11160930/1858773

2016-10-5 Linux Basic Learning-process and job management