as31: 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

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/as31 - from package: as31

You may install the required package with command apt-get install {package}
Error in other languages:
as31: bevel nie gevind nie
as31: comandă negăsită
as31: comando não encontrado
as31: commande introuvable
as31: command not found
as31: käsku ei ole
as31: không tìm thấy lệnh
as31: komanda nerasta
as31: Kommando nicht gefunden.
as31: kommandot finns inte
as31: komut yok
as31: nie znaleziono polecenia
as31: níor aimsíodh an t-ordú
as31: no se encontró la orden
as31: no s'ha trobat l'ordre
as31: opdracht niet gevonden
as31: parancs nem található
as31: perintah tidak ditemukan
as31: príkaz nenájdený
as31: příkaz nenalezen
as31: команда не найдена
as31: командата не е открита
as31: 命令找不到
as31: コマンドが見つかりません