netwatch: 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 Debian possible default full paths are:

/usr/sbin/netwatch - from package: netdiag

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

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