Linux process simple summary
Linux on the process has five states:
1. Run (running or waiting in the run queue)
2. Interrupt (Sleep, blocked, waiting for the formation of a condition or a signal is received)
3. Do not interrupt (received signal does not wake up and can not run, the process must wait until an interrupt occurs)
4. zombie (the process has been terminated, but the process descriptor to exist until the parent calls wait4 () system call after release)
5. Stop (process received SIGSTOP, SIGSTP, SIGTIN, after SIGTOU signal stops running)
ps command to view the current static system, which is being executed, as well as their implementation. You can not add any parameters.
ps -a: shows all the current terminal process information.
ps -u: displays process information in user-friendly format
ps -x: background processes running display parameters
I like to use to link directly to three parameters: ps -aux found this information more complete and more detailed.
USER: The process belongs to the user account
PID: The process number
% CPU: The percentage of CPU resources to process using out
% MEM: The percentage of physical memory occupied by the process
VSZ: The process using off virtual memory (Kbytes)
RSS: a fixed amount of memory (Kbytes) of the process takes
TTY: The above process is that the terminal operation, regardless of when the terminal is displayed, in addition, tty1-tty6 native who sign the above procedure, if it is pts / 0, etc., then by the network? ligated into the host program.
STAT: The current state of the program, the main state has
R: The program is currently operating, or be operating
S: This program is currently being sleep which (arguably idle state), but may be some signal (signal) to wake up.
T: The program is currently being detected or stopped
Z: The program should have been terminated, but his father was not the normal procedure to terminate him, resulting in a state zombie (Jiang corpse) Program
START: The process is triggered start time
TIME: The process of using the real time CPU operation
COMMAND: actual instructions of the program
23:59:58 Current time
up 10:22 system uptime, the format hours: minutes
2 user the current number of users logging
load average: 0.00, 0.00, 0.00 system load, that is, the average length of the task queue. Three values of 1 minute, 5 minutes, respectively, 15 minutes prior to the current average.
Number of total process
The number of processes running running
Process sleeping Sleep Number
Number stopped stopped process
zombie zombie number of processes
xx% us user space occupied by the percentage of CPU
xx% sy CPU kernel space occupancy percentage
Within xx% ni user process space, changed the process priority of CPU-percentage
xx% id CPU idle percentage
Percentage xx% wa waiting for input and output of the CPU time
xx% hi: hardware interrupt CPU occupancy percentage
xx% si: soft interrupt occupancy percentage
xx% st: virtual machine occupancy percentage
1004412k total amount of physical memory
The total amount of physical memory used 221404k used
783008k free amount of free memory
The amount of memory 17268k buffers used kernel cache
2031668k total total swap
0k used the total amount used swap
Total swap 2031608k free idle
The total amount of cached buffer swap 97902k, the contents of memory to be swapped out to the swap area, and later was changed into memory, but the used swap has not been covered, the value shall be the content already exists in memory the size of the swap, the corresponding memory again can no longer be written to swap when swapped out.
No. Column name Meaning
a PID process id
b PPID parent process id
c RUSER Real user name
User id d UID process owner
Username e USER process owner
F GROUP group name of the process owner
g TTY terminal name starts the process. The process was not started from the terminal is displayed as?
h PR Priority
i NI nice value. A negative value indicates a high priority, a positive value indicates a low priority
j P last used CPU, makes sense only in a multi-CPU environment
k% CPU last update to the current occupancy percentage of CPU time
L TIME CPU time used by the process in total, in seconds
m TIME + CPU time used by the process of total unit 1/100 sec
N% MEM Percentage of physical memory used by the process
O VIRT total virtual memory used by the process, the unit kb. VIRT = SWAP + RES
P SWAP process virtual memory in use, to be swapped out the size in kb.
q RES process uses, not swapped out of physical memory size, unit kb. RES = CODE + DATA
r CODE executable code amount of physical memory size, unit kb
S DATA section of executable code other than (data segment + stack) the amount of physical memory size, unit kb
t SHR shared memory size, unit kb
u nFLT number of page faults
v nDRT last write to the present, the number of pages have been modified.
w S process state (D = uninterruptible sleep, R = Run, S = sleep, T = trace / stop, Z = zombie process)
x COMMAND command name / command line
y WCHAN if the process is sleeping, it shows the system sleep function name
z Flags Task Flags, reference sched.h
Introduction to terminate the process
kill process ID: terminate a process
kill -9 process ID: forced to terminate a process
kill -u Username: terminate a user process
Here is a brief three common command to terminate the process.
Linux view a running path step process just three steps:
A: Process number to view the need to query the process, ps or top line also
Two: Linux when you start a process, the system creates a folder named PID in / proc, we will process the information in this folder.
cd / proc / PID: process to reach the appropriate directory.
Three: Run ls -l
cwd is a symbolic link process run directory.
exe symbolic link is the absolute path to execute the program.
cmdline is the command-line program to run when you enter the command.
environ record the process runtime environment variables.