class.x: 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
/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/class.x - from package: palp

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