html2pdbtxt: 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/bin/html2pdbtxt - from package: txt2pdbdoc

You may install the required package with command apt-get install {package}
Error in other languages:
html2pdbtxt: bevel nie gevind nie
html2pdbtxt: comandă negăsită
html2pdbtxt: comando não encontrado
html2pdbtxt: commande introuvable
html2pdbtxt: command not found
html2pdbtxt: käsku ei ole
html2pdbtxt: không tìm thấy lệnh
html2pdbtxt: komanda nerasta
html2pdbtxt: Kommando nicht gefunden.
html2pdbtxt: kommandot finns inte
html2pdbtxt: komut yok
html2pdbtxt: nie znaleziono polecenia
html2pdbtxt: níor aimsíodh an t-ordú
html2pdbtxt: no se encontró la orden
html2pdbtxt: no s'ha trobat l'ordre
html2pdbtxt: opdracht niet gevonden
html2pdbtxt: parancs nem található
html2pdbtxt: perintah tidak ditemukan
html2pdbtxt: príkaz nenájdený
html2pdbtxt: příkaz nenalezen
html2pdbtxt: команда не найдена
html2pdbtxt: командата не е открита
html2pdbtxt: 命令找不到
html2pdbtxt: コマンドが見つかりません