genpref-experimental: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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/genpref-experimental - from package: icewm-experimental

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