inc: 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/mu-mh/inc - from package: mailutils-mh
/usr/bin/mh/inc - from package: nmh

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

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