velvetg: command not found

Have You tried accessing the binary with the full path?

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/velvetg - from package: velvet

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