ypset: 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/sbin/ypset - from package: yp-tools

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

On Debian possible default full paths are:

/usr/sbin/ypset - from package: nis

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

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