command for supply the gas in the simulation box

Dear all users,

I need the command, for how to supply the gas in the simulation box

Dear all users,

I need the command, for how to supply the gas in the simulation box

here are all the commands that are available in LAMMPS. take a pick:
http://lammps.sandia.gov/doc/Section_commands.html#cmd_5

Fix deposit is one you can look at.

Steve