tcpdump_to_db: 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/tcpdump_to_db - from package: perl-Fsdb

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

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