rahistogram: 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/rahistogram - from package: argus-client

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

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