mimecat: 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/share/doc/mh-book/examples/mh/bin/mimecat - from package: mh-book

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

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