jnettop: 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/jnettop - from package: jnettop

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

On Debian possible default full paths are:

/usr/sbin/jnettop - from package: jnettop

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

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