httptest: 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/httptest - from package: dsbltesters

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

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