gpm-root: 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/gpm-root - from package: gpm

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

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