fix '-no-headers' typo in the ps flags

[stgarf]

... and simplify options (-Afl) passed to ps (down to just -A) since we're just passing the output straight off to wc -l anyways for a count.

-f causes the command arguments to be printed.

user@host:~$ ps -f
UID        PID  PPID  C STIME TTY          TIME CMD
user    12572  1754  0 02:51 pts/5    00:00:00 -bash
user    13344 12572  0 02:58 pts/5    00:00:00 ps -f

-l Long Format.

user@host:~$ ps
  PID TTY          TIME CMD
12572 pts/5    00:00:00 bash
13170 pts/5    00:00:00 ps

user@host:~$ ps -l
F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
0 S  1000 12572  1754  0  80   0 -  5329 wait   pts/5    00:00:00 bash
0 R  1000 13173 12572  0  80   0 -  7290 -      pts/5    00:00:00 ps

...neither are needed and possibly may result in unnecessary load on smaller devices ☹️ .