xstar: 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/xstar - from package: xstar

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

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