mhshow: 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/mh/mhshow - from package: nmh

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

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