twinkle: 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/twinkle - from package: twinkle

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

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