gropdf: 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/gropdf - from package: groff

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