update-yorickdoc: 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/update-yorickdoc - from package: yorick-doc

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

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