pkgdb-admin: 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/pkgdb-admin - from package: packagedb-cli

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

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