discover-pkginstall: 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:

/sbin/discover-pkginstall - from package: discover

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

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