openlp: 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/openlp - from package: openlp

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