yfrceta: 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/yfrceta - from package: patchy

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

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