xvinfo: 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/xvinfo - from package: xorg-x11-utils

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

On Debian possible default full paths are:

/usr/bin/xvinfo - from package: x11-utils

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

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