I would appreciate it if you could take a look at the details here.
Read all the contents of proc / [pid] Read all the contents of proc / [pid] ~ from attr to cpuset ~ Read all the contents of proc / [pid] ~ from cwd to loginuid ~ Read all the contents of proc / [pid] ~ from oom_adj to sessionid ~ Wrong, you can find more information here, that directory is no longer in use, I would appreciate it if you could comment if you have any information.
# sleep 365d > /dev/null &
[1] 3792
# ls /proc/3792
attr cwd map_files oom_adj schedstat task
autogroup environ maps oom_score sessionid timers
auxv exe mem oom_score_adj setgroups uid_map
cgroup fd mountinfo pagemap smaps wchan
clear_refs fdinfo mounts patch_state stack
cmdline gid_map mountstats personality stat
comm io net projid_map statm
coredump_filter limits ns root status
cpuset loginuid numa_maps sched syscall
# cd /proc/3792
setgroups
# cat setgroups
allow
It seems that the setgroups system call can be used when it is set to allow. setgroups will return a list of auxiliary groups. What is that? Believe it will be useful someday and remember.
smaps
cat smaps
00400000-00406000 r-xp 00000000 08:01 16801948 /usr/bin/sleep
Size: 24 kB
Rss: 0 kB
Pss: 0 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
Referenced: 0 kB
Anonymous: 0 kB
AnonHugePages: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 0 kB
VmFlags: rd ex mr mp me dw sd
00606000-00607000 r--p 00006000 08:01 16801948 /usr/bin/sleep
Size: 4 kB
...
This also seems to be the information of the memory used. Memory management seems to be difficult. Which one should I look at?
stack
# cat stack
[<ffffffffaa2cb09b>] hrtimer_nanosleep+0xbb/0x180
[<ffffffffaa2cb1f6>] SyS_nanosleep+0x96/0xb0
[<ffffffffaa98dede>] system_call_fastpath+0x25/0x2a
[<ffffffffffffffff>] 0xffffffffffffffff
It looks like the information on the stack in memory.
stat
# cat stat
3792 (sleep) S 1 3792 2132 0 -1 1077944320 284 0 0 0 0 0 0 0 20 0 1 0 31848330 110546944 65 18446744073709551615 4194304 4218500 140735872847584 140735872847112 140243604047856 0 0 0 0 18446744072269639835 0 0 17 0 0 0 0 0 0 6319400 6320704 8036352 140735872850184 140735872850195 140735872850195 140735872851949 0
statm
# cat statm
26989 65 47 6 0 78 0
It seems to be information about memory usage measured on a page-by-page basis.
status
# cat status
Name: sleep
Umask: 0022
State: S (sleeping)
Tgid: 3792
Ngid: 0
Pid: 3792
PPid: 1
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 256
Groups: 0
VmPeak: 107956 kB
VmSize: 107956 kB
...
It seems that you can see the basic information and operating status of the process. Perhaps if you look at this much, you can get a general idea of the situation.
syscall
# cat syscall
35 0x7fff9fb54d10 0x0 0x0 0x7fff9fb54760 0x0 0x0 0x7fff9fb54d08 0x7f8d023387f0
It seems that the addresses of the system call, stack pointer, program counter, etc. that are being executed are listed.
task
# ll task/
total 0
dr-xr-xr-x. 7 root root 0 Jan 12 04:48 3792
# ls task/3792/
attr cpuset io net patch_state setgroups uid_map
auxv cwd limits ns personality smaps wchan
cgroup environ loginuid numa_maps projid_map stack
children exe maps oom_adj root stat
clear_refs fd mem oom_score sched statm
cmdline fdinfo mountinfo oom_score_adj schedstat status
comm gid_map mounts pagemap sessionid syscall
There was a similar file in the 3792 process. It seems to be the relationship between processes and threads.
timers
It seems that you will see a list of timers that this process has.
In this environment, cat timers didn't show anything.
uid_map
This was introduced in gid_map before, so I will omit it.
wchan
# cat wchan
hrtimer_nanosleep
It's an abbreviation for wait channel. I didn't know any more information
It was hell because I had to write only if I didn't understand from the middle. My goal was to write it down for the time being, so I wrote it down in two days. When I turned it on at a later date, I was confident that I would never touch it again, so I patiently survived. I hope to add more information as soon as I can understand more information.
https://linuxjm.osdn.jp/html/LDP_man-pages/man5/proc.5.html http://man7.org/linux/man-pages/man7/user_namespaces.7.html http://man7.org/linux/man-pages/man2/setgroups.2.html
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