wmgenmenu: 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 CentOS possible default full paths are:

/usr/bin/wmgenmenu - from package: WindowMaker

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/wmgenmenu - from package: wmaker

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

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