download-entities.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 CentOS possible default full paths are:

/usr/bin/download-entities.pl - from package: perl-XML-Entities

You may install the required package with command yum install {package}

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