hylafax: 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/sbin/hylafax - from package: hylafax+

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

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