EDITCAP Use to edit a pcap file (split into 1000 packets):

> editcap -F pcap -c 1000 orignal.pcap
out_split,pcap

Use to edit a pcap file (split into 1 hour each packets):

> editcap -F pcap -t+3600 orignal.pcap
out_split.pcap

MERGECAP Use to merge multiple pcap files:

> mergecap -w merged_cap.pcap capl.pcap cap2.pcap
cap3.pcap