gv2gxl: 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/gv2gxl - from package: graphviz

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

On Debian possible default full paths are:

/usr/bin/gv2gxl - from package: graphviz

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

Error in other languages:
gv2gxl: bevel nie gevind nie
gv2gxl: comandă negăsită
gv2gxl: comando não encontrado
gv2gxl: commande introuvable
gv2gxl: command not found
gv2gxl: käsku ei ole
gv2gxl: không tìm thấy lệnh
gv2gxl: komanda nerasta
gv2gxl: Kommando nicht gefunden.
gv2gxl: kommandot finns inte
gv2gxl: komut yok
gv2gxl: nie znaleziono polecenia
gv2gxl: níor aimsíodh an t-ordú
gv2gxl: no se encontró la orden
gv2gxl: no s'ha trobat l'ordre
gv2gxl: opdracht niet gevonden
gv2gxl: parancs nem található
gv2gxl: perintah tidak ditemukan
gv2gxl: príkaz nenájdený
gv2gxl: příkaz nenalezen
gv2gxl: команда не найдена
gv2gxl: командата не е открита
gv2gxl: 命令找不到
gv2gxl: コマンドが見つかりません