purge_old_entries.pl: 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/share/doc/libpoet-perl/examples/blog/bin/purge_old_entries.pl - from package: libpoet-perl

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

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