psurface-smooth: 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/psurface-smooth - from package: psurface

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

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