http@: 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/bin/http@ - from package: ucspi-tcp-ipv6
/usr/bin/http@ - from package: ucspi-tcp

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

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