avg_showfile: command not found

Have You tried accessing the binary with the full path?

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_showfile - from package: python-libavg

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