orbit-ird: 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/orbit-ird - from package: ORBit

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

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