avg_checkspeed: 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/avg_checkspeed - from package: python-libavg

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

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