tf: 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/tf - from package: tinyfugue

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

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