dbfilediff: 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/dbfilediff - from package: perl-Fsdb

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

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