[HN Gopher] So, what can you do with a process ID?
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       So, what can you do with a process ID?
        
       Author : gcmeplz
       Score  : 20 points
       Date   : 2022-12-16 16:31 UTC (6 hours ago)
        
 (HTM) web link (will-keleher.com)
 (TXT) w3m dump (will-keleher.com)
        
       | tdoot wrote:
       | Interesting there's no mention of the _/ proc_ filesystem
       | (https://docs.kernel.org/filesystems/proc.html).
       | 
       |  _cat /proc/<pid>/environ_ would be a solid addition to this
       | list.
        
       | ghostpepper wrote:
       | My go-to incantation is `ps ajxf`, (truncated and edited) sample
       | output below                  PPID   PID  PGID   SID TTY
       | TPGID STAT   UID   TIME COMMAND           0     1     1     1 ?
       | -1 Ss       0   0:57 /sbin/init splash           1   978   978
       | 978 ?           -1 Ss       0   0:00 /usr/sbin/sshd -D
       | 978 11441 11441 11441 ?           -1 Ss       0   0:00  \_ sshd:
       | ghostpepper [priv]       11441 11445 11441 11441 ?           -1 S
       | 1000   0:00      \_ sshd: ghostpepper@pts/4       11445 11446
       | 11446 11446 pts/4    11641 Ss    1000   0:00          \_ -bash
       | 11446 11641 11641 11446 pts/4    11641 R+    1000   0:00
       | \_ ps ajxf
       | 
       | Another thing some might not know is that kill (the command /
       | syscall) can send a lot of other signals than KILL (the signal).
       | Not all processes know how to gracefully handle them, so you need
       | to be careful, but for example a lot of daemons can catch SIGHUP
       | and re-load their config file from disk.
        
       | hsfzxjy wrote:
       | And with strace -p pid you can somewhat "spy" on what a process
       | is doing.
        
       | crossingTime wrote:
       | When I was a chemist we used photoionization detectors to detect
       | VOCs in groundwater.
        
       | daniel-s wrote:
       | For a moment I thought the topic was about PID controllers. That
       | would have been cool.
       | 
       | If the blogging gods take requests I just made one.
        
         | dang wrote:
         | In the meantime, we've macroexpanded that acronym in the title
         | above.
        
       | yakubin wrote:
       | On Linux one of my favourite tools to display metrics about a
       | process in real time, such as cpu/memory/io utilisation, which
       | can also be broken down per thread (with friendly thread names
       | displayed if your application sets them), is pidstat from the
       | sysstat package.
        
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       (page generated 2022-12-16 23:01 UTC)