bihourly: 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/sbin/bihourly - from package: arpwatch

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

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