darkbat: 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/darkbat - from package: munipack

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

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