Linux System Management-process management

　　Process Management

Process: Program instructions running in CPU and memory are code that executes dynamically

Parent/Child process: a process can create one or more child processes

PID: ID number of the process

PPID: Parent Process ID Number

Linux consists of the following three processes:

1. Interactive process: a process initiated by a shell. The interactive process can be run either in the foreground or in the background.
2. Batch process: This process is not associated with a terminal and is a sequence of processes.
3. Daemon: A process that starts when the Linux system starts and runs in the background.

Command 1: View the number of processes Pstree

Format: pstree [options] [PID or user name]

Option:-A displays the full command line

-U lists the owning of the process

-p lists the PID of the process

Common format: PSTREE-AP [pid or user name]

　　　　　　

Command 2: View process snapshot PS

Format: PS [options]

Common options: Aux lists running processes (most detailed information)

-elf list running processes (PID and ppid are listed)

　　

　　

Status of the process in which the Stat column is represented

Status of R running

S is dormant and is awakened when needed

D non-disruptive hibernation, usually in the event of waiting for I/O

T Stop State

Z Zombie Status

Command 3: Process dynamic ranking Tool top

Format: Top [-D refresh interval (default 3 seconds)] [-u user Name]

　　

Entering the top command in the command-line environment enters the interactive mode of the top command, with the following common commands:

P,m descending order according to%cpu,%mem

T is in descending order based on the time consumed by the process

K Killer the process of the specified PID

Q exit

Records the average load of Linux for one minute, five minutes, and 15 minutes

Command 4: Retrieve process information Command pgrep

Format: pgrep [options] [query criteria]

Option:-L output process name and PID

　　　　　　

-U retrieves the process for the specified user

-T retrieves the specified terminal process

front and back scheduling of processes

Reception start: 1, enter the normal command line. 2. Occupy Terminal during Operation

Background start: 1, add the "&" symbol at the end of the command line. 2, the operation period does not occupy the terminal

Suspend current task (go to background and pause run): Shortcut key ctrl + Z

Terminate current task: Ctrl + C

View the background Tasks list: Jobs jobs-l [List pid of background tasks]

Restore a background task to the foreground run: FG FG [Task number]

Activating background suspended tasks: BG BG [Task number]

When a task ordinal is not specified, the default is the most recent background task

　　Close process

　　Kill process According to PID: Kill PID (Terminate process) kill-9 PID (Force end process)

Kill process by Process name: Killall [process name] (terminate process)

　　　　

Linux System Management-process management