fbo-readpixels: 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/fbo-readpixels - from package: piglit

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

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