nroff: 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 CentOS possible default full paths are:

/usr/bin/nroff - from package: groff

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/nroff - from package: groff-base

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

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