velvetoptimiser: 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/velvetoptimiser - from package: velvetoptimiser

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

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