mrc2mkr: 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/mrc2mkr - from package: libmarc-file-marcmaker-perl

You may install the required package with command apt-get install {package}
Error in other languages:
mrc2mkr: bevel nie gevind nie
mrc2mkr: comandă negăsită
mrc2mkr: comando não encontrado
mrc2mkr: commande introuvable
mrc2mkr: command not found
mrc2mkr: käsku ei ole
mrc2mkr: không tìm thấy lệnh
mrc2mkr: komanda nerasta
mrc2mkr: Kommando nicht gefunden.
mrc2mkr: kommandot finns inte
mrc2mkr: komut yok
mrc2mkr: nie znaleziono polecenia
mrc2mkr: níor aimsíodh an t-ordú
mrc2mkr: no se encontró la orden
mrc2mkr: no s'ha trobat l'ordre
mrc2mkr: opdracht niet gevonden
mrc2mkr: parancs nem található
mrc2mkr: perintah tidak ditemukan
mrc2mkr: príkaz nenájdený
mrc2mkr: příkaz nenalezen
mrc2mkr: команда не найдена
mrc2mkr: командата не е открита
mrc2mkr: 命令找不到
mrc2mkr: コマンドが見つかりません