netcap: 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/netcap - from package: libcap-ng-utils

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

On Debian possible default full paths are:

/usr/bin/netcap - from package: libcap-ng-utils

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

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