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

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