how to run tcpdump on background?

[esolve]

I have a script where I want to run tcpdump and then immediately run another command
however, tcpdump will cause the shell pause/hang
so the following command lines will have no chance to run

even if I use &, it doesn't help
are there any solutions?
thanks

[atreyu]

use GNU screen, i'd say. it is a terminal emulator that allows you to create a virtual terminal that you can run bash scripts and commands in and throw it in the background, great for stuff like this, e.g.:

screen -S "TCPDump" -dm tcpdump -i wlan0

this will start a screen named "TCPDump" and run it in the background (-dm) and the command passed to it will be "tcpdump -i wlan0".

you can see running screen sessions with:

screen -ls

and then reattach to the pid or the name of a session (listed in the "screen -ls" command) with, e.g.:

screen -r TCPDump

check out the man page ("man screen") to learn the many options available in screen.