avopkg: 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/avopkg - from package: avogadro

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

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