ypatchy: 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/ypatchy - from package: patchy

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

On Debian possible default full paths are:

/usr/bin/ypatchy - from package: nypatchy

You may install the required package with command apt-get install {package}

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