sabredav.php: 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/share/doc/php-sabre-dav-1.8.12/bin/sabredav.php - from package: php-sabre-dav

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

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