make-memtest86-boot-floppy: 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/make-memtest86-boot-floppy - from package: memtest86

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

Error in other languages:
make-memtest86-boot-floppy: bevel nie gevind nie
make-memtest86-boot-floppy: comandă negăsită
make-memtest86-boot-floppy: comando não encontrado
make-memtest86-boot-floppy: commande introuvable
make-memtest86-boot-floppy: command not found
make-memtest86-boot-floppy: käsku ei ole
make-memtest86-boot-floppy: không tìm thấy lệnh
make-memtest86-boot-floppy: komanda nerasta
make-memtest86-boot-floppy: Kommando nicht gefunden.
make-memtest86-boot-floppy: kommandot finns inte
make-memtest86-boot-floppy: komut yok
make-memtest86-boot-floppy: nie znaleziono polecenia
make-memtest86-boot-floppy: níor aimsíodh an t-ordú
make-memtest86-boot-floppy: no se encontró la orden
make-memtest86-boot-floppy: no s'ha trobat l'ordre
make-memtest86-boot-floppy: opdracht niet gevonden
make-memtest86-boot-floppy: parancs nem található
make-memtest86-boot-floppy: perintah tidak ditemukan
make-memtest86-boot-floppy: príkaz nenájdený
make-memtest86-boot-floppy: příkaz nenalezen
make-memtest86-boot-floppy: команда не найдена
make-memtest86-boot-floppy: командата не е открита
make-memtest86-boot-floppy: 命令找不到
make-memtest86-boot-floppy: コマンドが見つかりません