prayer-ssl-prune: 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/sbin/prayer-ssl-prune - from package: prayer

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

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