wmmon: 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/bin/wmmon - from package: wmmon

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

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