ebook: 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/ebook - from package: libebook-tools-perl

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

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