copytexsubimage: 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/copytexsubimage - from package: piglit

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

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