At the end of the previous mission use
saveStatus to record the player's gear. Then in the Initialization of the new mission use
loadStatus to return it to the player's inventory.
However, according to
Nominesine you should use
deleteStatus to make sure an entry is blank before writing to it with saveStatus.
deleteStatus "playerState"; player saveStatus "playerState"
player loadStatus "playerState"
NB. Like
init.sqs the game should automatically run
exit.sqs at the end of a mission.
If you fancy something more advanced try the WeaponPool Tutorial from
Vektorboson's Homepage. It's old (dating from December 2002), but shows the functioning of the Resistance campaign with weapons carrying over in the player's group.
Edit: corrected the command in init.sqs - thanks to Raptorsaurus for pointing it out.