velvetg_long: 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_long - from package: velvet-long

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