nette-tester: 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/nette-tester - from package: php-nette-tester

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

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