gnotski: 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/gnotski - from package: gnome-games-extra

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

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