rabbirc: 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 Debian possible default full paths are:

/usr/bin/rabbirc - from package: rabbit

You may install the required package with command apt-get install {package}

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