nyindex: 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/nyindex - from package: patchy

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

On Debian possible default full paths are:

/usr/bin/nyindex - from package: nypatchy

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

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