ifscheme: 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/ifscheme - from package: ifscheme

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

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