useradm.cgi: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/xymon/server/bin/useradm.cgi - from package: xymon

You may install the required package with command apt-get install {package}

Error in other languages:
useradm.cgi: bevel nie gevind nie
useradm.cgi: comandă negăsită
useradm.cgi: comando não encontrado
useradm.cgi: commande introuvable
useradm.cgi: command not found
useradm.cgi: käsku ei ole
useradm.cgi: không tìm thấy lệnh
useradm.cgi: komanda nerasta
useradm.cgi: Kommando nicht gefunden.
useradm.cgi: kommandot finns inte
useradm.cgi: komut yok
useradm.cgi: nie znaleziono polecenia
useradm.cgi: níor aimsíodh an t-ordú
useradm.cgi: no se encontró la orden
useradm.cgi: no s'ha trobat l'ordre
useradm.cgi: opdracht niet gevonden
useradm.cgi: parancs nem található
useradm.cgi: perintah tidak ditemukan
useradm.cgi: príkaz nenájdený
useradm.cgi: příkaz nenalezen
useradm.cgi: команда не найдена
useradm.cgi: командата не е открита
useradm.cgi: 命令找不到
useradm.cgi: コマンドが見つかりません