grops: 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/grops - from package: groff

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

On Debian possible default full paths are:

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

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

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