lp: 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/lp - from package: cups-client
/usr/bin/lp - from package: lprng

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

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