I would appreciate it if you could take a look at the details here. Read all the contents of proc / [pid]
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
cwd
# ll cwd
lrwxrwxrwx. 1 root root 0 Jan 11 13:12 cwd -> /root
A symbolic link to the process's current directory.
Since I ran it as the root user, it is / root.
The 3792 process seems to work as / root. Sounds dangerous.
environ
# cat environ
XDG_SESSION_ID=89SHELL=/bin/bashTERM=xtermHISTSIZE=1000USER=rootLS_COLORS=rs=0:di=01;34:ln=01;(abridgement)
# tr \\0 \\n < environ
XDG_SESSION_ID=89
SHELL=/bin/bash
TERM=xterm
HISTSIZE=1000
USER=root
LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;(abridgement)
MAIL=/var/spool/mail/root
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
PWD=/root
LANG=en_US.UTF-8
HISTCONTROL=ignoredups
SHLVL=1
HOME=/root
LOGNAME=root
LESSOPEN=||/usr/bin/lesspipe.sh %s
_=/bin/sleep
The value of the environment variable. It seems to be separated by a null character. I don't know if it's cat.
The same content was confirmed with ps ex | grep 3792.
Converting \ 0 (NULL) to \ n (line feed) as tr \\ 0 \\ n <environ makes it easier to read.
exe
# ll exe
lrwxrwxrwx. 1 root root 0 Jan 11 13:12 exe -> /usr/bin/sleep
Executable file symbolic
fd
# ll fd
total 0
lrwx------. 1 root root 64 Jan 11 12:49 0 -> /dev/pts/0 (deleted)
l-wx------. 1 root root 64 Jan 11 12:49 1 -> /dev/null
lrwx------. 1 root root 64 Jan 11 14:26 2 -> /dev/pts/0 (deleted)
A subdirectory containing entries for each file opened by the process. The file descriptor is the file name, which is a symbolic link to the actual file. Therefore, 0 is the standard input, 1 is the standard output, 2 is the standard error output, and so on. Quote [https://linuxjm.osdn.jp/html/LDP_man-pages/man5/proc.5.html]
fd: = Abbreviation for File Descriptor. This is convenient. Can be used when you want to check input / output
fdinfo
# ll fdinfo/
total 0
-r--------. 1 root root 0 Jan 11 12:49 0
-r--------. 1 root root 0 Jan 11 12:49 1
-r--------. 1 root root 0 Jan 11 12:49 2
# cat fdinfo/0 fdinfo/1 fdinfo/2
pos: 0
flags: 0100002
mnt_id: 23
pos: 0
flags: 0100001
mnt_id: 20
pos: 0
flags: 0100002
mnt_id: 23
With the above information, it seems that the process can identify the file descriptor.
gid_map,uid_map
# cat gid_map
0 0 4294967295
# cat uid_map
0 0 4294967295
It seems to describe the mapping information required to use different UIDs and GIDs inside and outside the user namespace. This will be helpful, so I'll read it later. https://gihyo.jp/admin/serial/01/linux_containers/0016
io
# cat io
rchar: 2012
wchar: 0
syscr: 7
syscw: 0
read_bytes: 0
write_bytes: 0
cancelled_write_bytes: 0
This file displays process I / O statistics. ... rchar: number of characters to read wchar: number of characters to write syscr: number of read system calls syscw: number of write system calls read_bytes: number of bytes to read write_bytes: number of bytes to write cancelled_write_bytes: ... (partially omitted) https://linuxjm.osdn.jp/html/LDP_man-pages/man5/proc.5.html
The last one should be "the number of bytes that failed to write".
limits
# cat limits
Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size 0 unlimited bytes
Max resident set unlimited unlimited bytes
Max processes 2288 2288 processes
Max open files 1024 4096 files
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 2288 2288 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us
It summarizes the resource limits of the process.
loginuid
# cat loginuid
1000
Who is the uid 1000
# cat /etc/passwd | grep 1000
inahy:x:1000:1001::/home/inahy:/bin/bash
It was my uid when I logged in to ssh. Currently, it is su to [inahy]-> [root]. What are you going to use it for?
I wasn't feeling well and had to copy and paste. I would like to make corrections later.
http://man7.org/linux/man-pages/man5/proc.5.html https://gihyo.jp/admin/serial/01/linux_containers/0016 http://manpages.ubuntu.com/manpages/bionic/ja/man5/proc.5.html
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