psf: 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/psf - from package: tcm

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

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