idfilter: 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/idfilter - from package: ladr4-apps
/usr/bin/idfilter - from package: topp

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

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