doscan: 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/doscan - from package: doscan

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

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