znc-buildmod: 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/znc-buildmod - from package: znc-devel

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

On Debian possible default full paths are:

/usr/bin/znc-buildmod - from package: znc-dev

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

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