dbrvstatdiff: 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/dbrvstatdiff - from package: perl-Fsdb

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

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