debiandoc2text: 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/debiandoc2text - from package: debiandoc-sgml

You may install the required package with command apt-get install {package}
Error in other languages:
debiandoc2text: bevel nie gevind nie
debiandoc2text: comandă negăsită
debiandoc2text: comando não encontrado
debiandoc2text: commande introuvable
debiandoc2text: command not found
debiandoc2text: käsku ei ole
debiandoc2text: không tìm thấy lệnh
debiandoc2text: komanda nerasta
debiandoc2text: Kommando nicht gefunden.
debiandoc2text: kommandot finns inte
debiandoc2text: komut yok
debiandoc2text: nie znaleziono polecenia
debiandoc2text: níor aimsíodh an t-ordú
debiandoc2text: no se encontró la orden
debiandoc2text: no s'ha trobat l'ordre
debiandoc2text: opdracht niet gevonden
debiandoc2text: parancs nem található
debiandoc2text: perintah tidak ditemukan
debiandoc2text: príkaz nenájdený
debiandoc2text: příkaz nenalezen
debiandoc2text: команда не найдена
debiandoc2text: командата не е открита
debiandoc2text: 命令找不到
debiandoc2text: コマンドが見つかりません