gvpr: 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/gvpr - from package: graphviz

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

On Debian possible default full paths are:

/usr/bin/gvpr - from package: graphviz

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

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