What is it?

The pair of programs (in single executable) demonstrating AF_UNIX socket feature of sharing file descriptors.

Examples

• Transmit file content.

  Start receiver on /tmp/socket:

   recvfd /tmp/socket
  

  Send file:

   sendfd -f input.txt /tmp/socket
  

• Send specific descriptor.

  Start receiver on /tmp/socket:

   recvfd /tmp/socket
  

  Open descriptor using exec (manpage):

   exec 3< input.txt
  

  Send it:

   sendfd -d 3 /tmp/socket
  

• Resend descriptor to the other program.

  Start receiver on /tmp/socket with -e switch and provide command to start child:

   recvfd -e -s /tmp/socket -- python3 -c 'print("first line:", input())'
  

  Send something:

   echo "hello python" | sendfd /tmp/socket