top and htop are commonly used tools to monitor processes and computer resources, but why is the status of top itself always R (in the S column of the top)? For example, here is a screenshot of the top command:
top - 12:42:33 up 2:48, 1 user, load average: 0,11, 0,17, 0,17
Tasks: 319 total, 1 running, 318 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1,1 us, 0,1 sy, 0,0 ni, 98,8 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Mem : 15968,5 total, 4031,8 free, 2196,1 used, 9740,7 buff/cache
MiB Swap: 122069,0 total, 122069,0 free, 0,0 used. 13325,4 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2264 xxxxxx 20 0 2784640 320344 184092 S 6,0 2,0 9:14.83 Web Content
2195 xxxxxx 20 0 3996144 481160 197788 S 2,7 2,9 7:46.13 firefox
1704 root 20 0 227712 101204 82140 S 1,3 0,6 3:26.54 Xorg
2993 xxxxxx 20 0 817416 54452 41724 S 1,0 0,3 0:04.27 gnome-terminal-
1856 xxxxxx 20 0 4521152 385832 123440 S 0,7 2,4 2:39.79 gnome-shell
1202 root -51 0 0 0 0 S 0,3 0,0 0:52.07 irq/44-nvidia
5048 xxxxxx 20 0 11980 3888 3132 R 0,3 0,0 0:00.12 top
1 root 20 0 167972 11864 8480 S 0,0 0,1 0:03.91 systemd
2 root 20 0 0 0 0 S 0,0 0,0 0:00.00 kthreadd
3 root 0 -20 0 0 0 I 0,0 0,0 0:00.00 rcu_gp
4 root 0 -20 0 0 0 I 0,0 0,0 0:00.00 rcu_par_gp
6 root 0 -20 0 0 0 I 0,0 0,0 0:00.00 kworker/0:0H-kblockd
9 root 0 -20 0 0 0 I 0,0 0,0 0:00.00 mm_percpu_wq
10 root 20 0 0 0 0 S 0,0 0,0 0:00.09 ksoftirqd/0
11 root 20 0 0 0 0 I 0,0 0,0 0:01.49 rcu_sched
12 root rt 0 0 0 0 S 0,0 0,0 0:00.02 migration/0
13 root -51 0 0 0 0 S 0,0 0,0 0:00.00 idle_inject/0
From the source code of top (procps/top), it gets process statuses from the file /proc/<pid>/stat, while the status of top, for most of the time, is S (sleeping) if it is continuously printed with the following command:
watch -n.1 "cat /proc/<top-pid>/stat | grep -o \"[S|R]\""
Well... if you are running top (or htop), and top (or htop) gets its own status from /proc/self/stat... then it must be running, otherwise how would it be possible that it got its status while not running? The sole fact that a process is reading its own status means that the status must be running at the time of reading.
You can try this with other programs too, if you want:
$ cat /proc/self/stat
32482 (cat) R ...
$ head /proc/self/stat
32491 (head) R ...
$ tail /proc/self/stat
32497 (tail) R ...
$ less /proc/self/stat
32503 (less) R ...