gvpack: 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 CentOS possible default full paths are:

/usr/bin/gvpack - from package: graphviz

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/gvpack - from package: graphviz

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

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