calibre-complete: 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/bin/calibre-complete - from package: calibre

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