diffindex-download: 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/diffindex-download - from package: apt-file

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

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