unroff: 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/unroff - from package: troffcvt

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

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