nisserver-plugin-defs: 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/nisserver-plugin-defs - from package: slapi-nis

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

On Debian possible default full paths are:

/usr/sbin/nisserver-plugin-defs - from package: slapi-nis

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

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