hepdb: 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/hepdb - from package: cernlib-packlib

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

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