mkr2mrc: 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/mkr2mrc - from package: libmarc-file-marcmaker-perl

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

Error in other languages:
mkr2mrc: bevel nie gevind nie
mkr2mrc: comandă negăsită
mkr2mrc: comando não encontrado
mkr2mrc: commande introuvable
mkr2mrc: command not found
mkr2mrc: käsku ei ole
mkr2mrc: không tìm thấy lệnh
mkr2mrc: komanda nerasta
mkr2mrc: Kommando nicht gefunden.
mkr2mrc: kommandot finns inte
mkr2mrc: komut yok
mkr2mrc: nie znaleziono polecenia
mkr2mrc: níor aimsíodh an t-ordú
mkr2mrc: no se encontró la orden
mkr2mrc: no s'ha trobat l'ordre
mkr2mrc: opdracht niet gevonden
mkr2mrc: parancs nem található
mkr2mrc: perintah tidak ditemukan
mkr2mrc: príkaz nenájdený
mkr2mrc: příkaz nenalezen
mkr2mrc: команда не найдена
mkr2mrc: командата не е открита
mkr2mrc: 命令找不到
mkr2mrc: コマンドが見つかりません