Are you asking yourself, which argument is used to set the "full name" in pure-ftpd?
The full name is shown in in the pure-pw list command and is helpful for a description:
global /srv/www/websites/./ Global View
web1 /srv/www/websites/web1/./ web1.example.com
web2 /srv/www/websites/web2/./ web2.example.com
web3 /srv/www/websites/web3/./ web3.example.com
Of course you have checked the man page, but it only describes this:
pure-pw useradd login [-f passwd_file] [-F puredb_file] -u uid [-g gid]
-D/-d home_directory [-c gecos]
[-t download_bandwidth] [-T upload_bandwidth]
[-n max number_of_files] [-N max_Mbytes]
[-q upload_ratio] [-Q download_ratio]
[-r /[,/]...] [-R /[,/]...]
[-i /[,/]...] [-I /[,/]...]
[-z -] [-m]
As stupid as it sounds, but I couldn't find any document defining which parameter is used for the full name.
I only found the following hint on the official pure-ftpd documentation for Virtual Users:
Once virtual users have been created, you can edit their info. For instance
you can add bandwidth throttling, change quotas, add their full name, update
This description can cause some confusion, because you can actually add "full name" during the creation, not only after a virtual user has already been created.
After just try'n'err, I found out that the magic parameter is [-c] which was probably named for "comment", although pure-ftpd calls it "full name". So with -c the full name can be set during creation:
pure-pw useradd web4 -u ftpuser -g ftpgroup -m -d /srv/www/websites/web4/ -c "web4.example.com"
This can be verified with the pure-pw show command:
pure-pw show web4
Login : web4
Password : $2a$07$IIyR6Stseeq2TmQ8V8vGLu/dAs0N8Rt9z0zSpSpY5oS.7hu7y7v/6
UID : 1000 (ftpuser)
GID : 1001 (ftpgroup)
Directory : /srv/www/websites/web4/./
Full name : web4.example.com