velveth: 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/velveth - from package: velvet

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

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