September 2009
Beginner
942 pages
85h 34m
English
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Coprocesses and Sockets
gawk allows you to open a two-way pipe to another process, called a coprocess. This is done with the |& operator used with getline and print or printf.
print database command |& "db_server"
"db_server" |& getline responseIf the command used with |& is a filename beginning with /inet/, gawk opens a TCP/IP connection. The filename should be of the following form:
/inet/protocol/lport/hostname/rport
The parts of the filename are:
- protocol
One of tcp, udp or raw, for TCP, UDP, or raw IP sockets, respectively. Note: raw is currently reserved but unsupported.
- lport
The local TCP or UPD port number to use. Use 0 to let the operating system pick a port.
- hostname
The name or IP address of the remote host to connect to.
- rport
The port (application) on the remote host to connect to. A service name (e.g., tftp) is looked up using the C getservbyname( ) function.
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