htadd: command not found

Have You tried accessing the binary with the full path?

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/lib/axiom-20140801/bin/htadd - from package: axiom-hypertex

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