compiz-gtk: 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/compiz-gtk - from package: compiz-gnome

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

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