gl30basic: 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/lib64/piglit/bin/gl30basic - from package: piglit

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

Error in other languages:
gl30basic: bevel nie gevind nie
gl30basic: comandă negăsită
gl30basic: comando não encontrado
gl30basic: commande introuvable
gl30basic: command not found
gl30basic: käsku ei ole
gl30basic: không tìm thấy lệnh
gl30basic: komanda nerasta
gl30basic: Kommando nicht gefunden.
gl30basic: kommandot finns inte
gl30basic: komut yok
gl30basic: nie znaleziono polecenia
gl30basic: níor aimsíodh an t-ordú
gl30basic: no se encontró la orden
gl30basic: no s'ha trobat l'ordre
gl30basic: opdracht niet gevonden
gl30basic: parancs nem található
gl30basic: perintah tidak ditemukan
gl30basic: príkaz nenájdený
gl30basic: příkaz nenalezen
gl30basic: команда не найдена
gl30basic: командата не е открита
gl30basic: 命令找不到
gl30basic: コマンドが見つかりません