lp-shell: 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/lp-shell - from package: lptools

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