Today go through the commands to monitor processes and how to handle them

• ps – It reports the snapshot of the current process
• init- It the parent process of all the processes.
• pstree – Same as ps but list the process in form of tree with more details.
• top- List down all the process running, update the snapshot after a while.
• Kill – it signals the process
  • INT – 2 -Interrupt, stop running
  • TERM – 15 – ask a process to exit gracefully
  • KILL – 9 – force the process to stop running
  • TSTP – 18 – request the process to stop temporarily
  • HUP – 1 – Hang up
• nice – Every process run has priority and with nice we can control this priority, it ranges from +19(very nice) to -20(not very nice) decreased niceness higher the priority
• renice- change the priority of the existing process

>> top
PID  User  PR  NI  VIRT     RES     SHR     S  %CPU %MEM Time+ Command
3911 user  20   0 2855988 206872 141304 S  72.2  2.6   7:15.09 Web Content                                                                       
31980 user  20   0 3703988 509176 188188 S  33.3  6.3  49:36.10 firefox                                                                           
 2839 user  20   0 2834092 191744 128268 S  27.8  2.4  16:13.39 Web Content    

>>ps
  PID TTY          TIME CMD
 2418 pts/2    00:00:00 zsh
 4318 pts/2    00:00:00 ps

>> pstree | less
systemd-+-NetworkManager-+-dhclient
        |                |-dnsmasq---dnsmasq
        |                |-{gdbus}
        |                `-{gmain}
        |-accounts-daemon-+-{gdbus}
        |                 `-{gmain}
        |-acpid
        |-agetty
        |-apache2---2*[apache2---26*[{apache2}]]
        |-at-spi-bus-laun-+-{dconf worker}
        |                 |-{gdbus}
        |                 `-{gmain}
...
>> nice -n 10 long-running-command &
>>renice 20 2984
>>renice 15 -u mike # changing  niceness for all process of mike user
>> kill -9 PID

#shell #dgplug #ilugc