displayfont: command not found

Have You tried accessing the binary with the full path?

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/displayfont - from package: console-cyrillic

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