How-to: Connect via Unix Domain Sockets

While REPLy defaults to a TCP server, you can also run it over Unix domain sockets. This is highly recommended for local editor integrations because it:

Avoids port conflicts.
Provides a file-based security boundary (only users with read/write access to the socket file can connect).

Starting a Unix Socket Server

Instead of passing host and port to REPLy.serve, use the socket_path argument:

using REPLy

# The socket file will be created automatically.
# Any existing file at this path will be overwritten.
socket_path = "/tmp/reply.sock"

server = serve(socket_path=socket_path)
println("REPLy listening on $socket_path")

wait(Condition())

Note: The server applies restrictive permissions (0o600) to the socket file so that only the user who started the server can interact with it.

Connecting from the Terminal

You can interact with the Unix socket using netcat (with the -U flag) or socat:

# Using netcat
printf '%s\n' '{"op":"eval","id":"demo-1","code":"1 + 1"}' | nc -U /tmp/reply.sock

# Using socat
printf '%s\n' '{"op":"eval","id":"demo-1","code":"1 + 1"}' | socat - UNIX-CONNECT:/tmp/reply.sock

The expected response is identical to the TCP transport:

{"id":"demo-1","value":"2","ns":"##REPLySession#..."}
{"id":"demo-1","status":["done"]}

Cleaning Up

When you call close(server) from Julia, the socket file is automatically deleted:

close(server)
# /tmp/reply.sock is now gone

Next Steps

See the Tutorial: Building a Custom Client to learn how to communicate with the socket programmatically from Julia.