Starting with version 3.1 of gawk, awk programs can open a two-way TCP/IP connection, acting as either a client or a server. This is done using a special file name of the form:
/inet/protocol/local-port/remote-host/remote-port
The protocol is one of ‘tcp’, ‘udp’, or ‘raw’, and the other fields represent the other essential pieces of information for making a networking connection. These file names are used with the ‘|&’ operator for communicating with a coprocess (see Two-way I/O). This is an advanced feature, mentioned here only for completeness. Full discussion is delayed until TCP/IP Networking.