ylist: command not found

Have You tried accessing the binary with the full path?

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/ylist - from package: patchy

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