sdoc: 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/sdoc - from package: ruby-sdoc

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