yadifa: 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/yadifa - from package: yadifa-tools

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

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