icemon: 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/icemon - from package: icecc-monitor

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

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