httpd_log_demux.php: 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/gforge/bin/httpd_log_demux.php - from package: gforge-common

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

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