xvarstar: 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 CentOS possible default full paths are:

/usr/bin/xvarstar - from package: xvarstar

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