TTY: Terminal "?" is a daemon, deamon has no terminal
VSZ: occupies virtual memory size
RSS: Occupied memory size
ps–axf: view process tree
ps –axm: list threads
pspid: show pid process
pstree : display the process tree
top : Dynamic monitoring process
Time System started time Number of users Current system load… Zombie process
96.0id: CPU resource idle ratio; memory and Swap
Monitor a specific user: enter u, enter user name, enter
Terminate the specified process: enter k, enter the process number to be terminated
Specify the system status update time: top -d 10: 1 update every 10 seconds
When top is running, you can control the display mode of the process through the internal command of top:
l: Turn on or off the top information on the first line of the first part
t: Turn on or off the second line of Tasks and the third line of Cpus information in the first part
m: Turn on or off the Swap information in the fourth line of the first part and the fifth line of Mem
N: Processes are arranged in order of PID size
P: Sort processes by CPU usage size
M: Sort processes by memory usage size
q: quit top
top-p pid: only monitor pid threads
vmstat: Linux system monitoring tool, is a tool to view the usage of virtual memory vm
In Linux memory management, mainly through "Paging" and "Swap Swaping", Paging: swap pages that are not frequently used in memory to disk, Swaping: swap the entire process to disk
Page-out: paging to disk; Page-in: paging back to memory
vmstat2 10：
r: The number of processes in the run queue exceeds the number of CPUs, resulting in a CPU bottleneck
b: The number of blocked processes waiting for IO, the blocked process
swpd: The number of virtual memory KB currently used, if it is greater than 0, it means that the machine memory is insufficient
free: the number of KB of physical memory currently free
buff: buffer memory size
cache: the memory size of the cache
si: The size of the virtual memory that swapin reads from the swap area per second. If it is greater than 0, it means that the physical memory is not enough.
so: swapout The size of the swap area written from the virtual memory to the swap area per second. If it is greater than 0, it means that the physical memory is not enough.
bi: blockin The total amount of data read into memory from the block device per second (read from disk)
bo:blockout The total amount of blocks written from memory to block devices per second (writes to disk)
in: interrupts per second
cs: context switches per second
us: user user process execution time
sy: system system process execution time
id: idle cpu idle time
wa: wait cpu wait IO time
Via /proc/cpuinfo : View CPU performance
grep 'model name'/proc/cpuinfo: View the number of CPU and CPU cores
jstack ：
jps: Find out the pid of the java process
top –p pid: observe the process situation
Shift + h : show all threads of the process
Convert the thread id to 16 processes, such as thread id 3720 == 0x7d0, pay attention to lowercase
jstack pid | grep -A 10 0x7d0: Query the status of a specific thread, which can basically locate the problem of the program
Learn about other JVM monitoring tools when needed
kill process number : to terminate the process, it is essentially a negotiated exit, not a forced exit
kill-9 (KILL) Process ID: send SIGKILL signal to force termination of process
killall process number: kill process and child processes
kill–STOP pid: send a SIGSTOP signal to suspend the background process
kill --CONT pid: resume a process that was suspended in the background
kill–l：list available signals
Kill signal description:
2）SIGINT：^C sends a SIGINT to all the processes in theforeground process group. To do the equivalent with kill，kill –SIGINT pid（OS-level concept）or to the job，kill –SIGINT %（shell-level concept，the pipeline ended with&）
man command : command manual
info command : View command documentation online
Enter / : Gegexp search
stty –a：get all the terminal controlcharacter assignments
For example, intr = ^C, susp = ^Z, etc.
free -m: View memory usage
Memory description file: cat /proc/meminfo: memory usage of the machine
/proc/pid/maps: Displays the virtual addresses occupied by the current process
/proc/pid/statm: memory occupied by the process
Linux free memory: free + buffers + cached
export : set or display environment variables (temporary)
exportPAHT=&PATH:&HOME/bin:root/test:set the PATH environment variable
If export is written to: /etc/profile or /etc/bashrc globally, then for all users, the environment variable will take effect permanently
If you write export to: /home/zzjie/.bashrc or .bash_profile, it is only valid for the user environment variable logged in by zzjie
echo $PATH: View the PATH environment variable
/etc/profile: Set the environment information for each user of the system, when the user logs in for the first time, this file is executed
/etc/bashrc: execute this file for every user running a bash shell, this file is read when the bash shell is opened
/zzjie/profile: Environment settings for zzjie users
/zzjie/bashrc: The bash shell configuration of the zzjie user, which initializes bash, such as bash code completion, bash aliases, etc.
/zzjie/bash_logout: This file is executed every time the user exits the bash shell
alias : specify an alias
aliasdump='mysqldump –u root –p db > /home/date.bak': Specify the database backup operation alias dump
aliassubl="/home/zzjie/Downloads/Sublime\ Text\ 2/Sublime\ Text\2/sublime_text"
shell wildcard : *?
reptyr：reptyr is a utilityfor taking an existing running program and attaching it to a new terminal
iptraf : Network measurement tool
iptraf–g：
iptraf–d eth0：
Notes : The command is finally executed in the Linux kernel, but first passed to the shell parser and then to the Kernel