lily-rebuild-pdfs: 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/lily-rebuild-pdfs - from package: texlive-music

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

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