prof: 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/prof - from package: profphd

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

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