mred-text: 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/mred-text - from package: racket

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

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