Shell: Day #5
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