cPanel
To count users, run the following command:
grep -Po '^(?<!#)\s\w+\s(?=:)' /etc/userplans | wc -l
Also, it may be useful to list users. To do so, run the following command:
cut -d":" -f1 /etc/userplans | sort -n | uniq
Plesk
To count users, run the following command:
plesk db "SELECT COUNT(DISTINCT cl_id) FROM domains"
DirectAdmin
To count users, run the following command:
cut -d":" -f2 /etc/virtual/domainowners | sort -n | uniq | wc -l
Also, it may be useful to list users. To do so, run the following command:
cut -d":" -f2 /etc/virtual/domainowners | sort -n | uniq
CyberPanel
To count users, run the following command:
cat /etc/passwd