troff: 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/troff - from package: groff

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

On Debian possible default full paths are:

/usr/bin/troff - from package: groff-base
/usr/lib/plan9/bin/troff - from package: 9base

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

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