dbmerge2: 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/dbmerge2 - from package: perl-Fsdb

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

Error in other languages:
dbmerge2: bevel nie gevind nie
dbmerge2: comandă negăsită
dbmerge2: comando não encontrado
dbmerge2: commande introuvable
dbmerge2: command not found
dbmerge2: käsku ei ole
dbmerge2: không tìm thấy lệnh
dbmerge2: komanda nerasta
dbmerge2: Kommando nicht gefunden.
dbmerge2: kommandot finns inte
dbmerge2: komut yok
dbmerge2: nie znaleziono polecenia
dbmerge2: níor aimsíodh an t-ordú
dbmerge2: no se encontró la orden
dbmerge2: no s'ha trobat l'ordre
dbmerge2: opdracht niet gevonden
dbmerge2: parancs nem található
dbmerge2: perintah tidak ditemukan
dbmerge2: príkaz nenájdený
dbmerge2: příkaz nenalezen
dbmerge2: команда не найдена
dbmerge2: командата не е открита
dbmerge2: 命令找不到
dbmerge2: コマンドが見つかりません