named socket

README.org

@@ -100,10 +100,20 @@ On first use, ~mxp~ boots a lightweight TCP eval server inside your running Emac
 The server starts automatically - no manual ~M-x~ step required. If the socket is unavailable (e.g., bash built without ~/dev/tcp~ support), ~mxp~ falls back to ~emacsclient~ transparently.
 
 #+attr_html: :width 50%
-| Variable      | Default | Description                                   |
-|---------------+---------+-----------------------------------------------|
-| ~MXP_PORT~      | ~17394~   | TCP port for the eval server (localhost only) |
-| ~MXP_NO_SOCKET~ | (unset) | Set to ~1~ to force ~emacsclient~-only mode       |
+| Variable          | Default | Description                                         |
+|-------------------+---------+-----------------------------------------------------|
+| ~MXP_PORT~          | ~17394~   | TCP port for the eval server (localhost only)       |
+| ~MXP_NO_SOCKET~     | (unset) | Set to ~1~ to force ~emacsclient~-only mode             |
+| ~EMACS_SOCKET_NAME~ | (unset) | Named socket for ~emacsclient -s~ (e.g., daemon name) |
+
+You can also pass ~-s~ / ~--socket-name~ on the command line:
+
+#+begin_src shell
+echo "hello" | mxp -s myserver "*my-buffer*"
+mxp --socket-name myserver --from "*my-buffer*"
+#+end_src
+
+This is useful when the Emacs daemon was started with a specific socket name, e.g., ~emacs --daemon=myserver~.
 
 To stop the server manually:
 

changelog.org

@@ -7,6 +7,7 @@ All notable changes to this project will be documented in this file.
 * [0.6.0] - 2026-04-06
 
 ** Added
+- ~-s~ / ~--socket-name~ flag and ~EMACS_SOCKET_NAME~ env var for connecting to a named Emacs daemon socket ([[https://github.com/agzam/mxp/issues/1][#1]])
 - Persistent TCP socket transport between ~mxp~ and Emacs
 - Auto-bootstrapping: ~mxp~ starts a lightweight eval server inside Emacs on first use (no manual ~M-x~ required)
 - All communication goes over a single persistent connection per invocation via bash's ~/dev/tcp~

mxp

@@ -11,6 +11,7 @@ CHUNK_SIZE=100
 STREAM_TIMEOUT=0.3
 MXP_PORT="${MXP_PORT:-17394}"
 MXP_SOCK_FD=""
+EMACS_SOCKET_NAME="${EMACS_SOCKET_NAME:-}"
 
 usage() {
   cat << EOF
@@ -31,6 +32,7 @@ OPTIONS:
   -f, --from BUFFER     Read from buffer (name or regex) and output to stdout
   -a, --append          Append to buffer instead of replacing content
   -p, --prepend         Prepend to buffer (insert at the beginning)
+  -s, --socket-name NAME  Connect to Emacs daemon socket NAME
   -F, --force           Overwrite existing buffer (skip conflict resolution)
   -h, --help            Show this help message
   -v, --version         Show version
@@ -85,6 +87,15 @@ die() {
   exit 1
 }
 
+# Wrapper for emacsclient - passes -s flag when socket name is set
+run_emacsclient() {
+  if [ -n "$EMACS_SOCKET_NAME" ]; then
+    command emacsclient -s "$EMACS_SOCKET_NAME" "$@"
+  else
+    command emacsclient "$@"
+  fi
+}
+
 # Find the actual script location, resolving symlinks
 find_script_location() {
   local script="$0"
@@ -284,7 +295,7 @@ MXP_ELISP
   elisp="${elisp//MXP_PORT_PLACEHOLDER/$port}"
   local encoded
   encoded=$(printf '%s' "$elisp" | encode_for_elisp)
-  emacsclient --eval \
+  run_emacsclient --eval \
     "(eval (read (decode-coding-string (base64-decode-string \"$encoded\") 'utf-8)))" \
     >/dev/null 2>&1 || return 1
   sleep 0.1
@@ -343,7 +354,7 @@ emacs_eval() {
     mxp_disconnect
   fi
   # Fallback: "$code" preserves embedded quotes as literal characters
-  emacsclient --eval "$code" 2>/dev/null
+  run_emacsclient --eval "$code" 2>/dev/null
 }
 
 # Verify Emacs is reachable and set up the best transport
@@ -355,7 +366,7 @@ init_emacs_connection() {
     mxp_ensure_connection && return 0
   fi
   # Socket unavailable - verify emacsclient can reach Emacs
-  if ! emacsclient --eval "t" &> /dev/null; then
+  if ! run_emacsclient --eval "t" &> /dev/null; then
     die "Cannot connect to Emacs server. Start Emacs daemon with: emacs --daemon"
   fi
 }
@@ -473,10 +484,10 @@ open_mode() {
   # Open in Emacs (emacsclient -n handles frame management and interactive prompts
   # correctly, unlike find-file from a process filter context)
   if [ -d "$path" ]; then
-    emacsclient -n "$path" &>/dev/null || die "Failed to open '$path'"
+    run_emacsclient -n "$path" &>/dev/null || die "Failed to open '$path'"
     echo "Opened directory in Emacs: $path"
   else
-    emacsclient -n "$path" &>/dev/null || die "Failed to open '$path'"
+    run_emacsclient -n "$path" &>/dev/null || die "Failed to open '$path'"
     echo "Opened file in Emacs: $path"
   fi
 }
@@ -635,6 +646,10 @@ main() {
       -p|--prepend)
         prepend="true"
         ;;
+      -s|--socket-name)
+        shift
+        EMACS_SOCKET_NAME="$1"
+        ;;
       -F|--force)
         force="true"
         ;;

test-mxp.sh

@@ -182,6 +182,12 @@ else
   fail "Version missing"
 fi
 
+if $SCRIPT --help | grep -q "\-s, --socket-name"; then
+  pass "Help shows -s/--socket-name option"
+else
+  fail "Help missing -s/--socket-name option"
+fi
+
 # Test 2: Write mode - pipe to new buffer
 section "Test 2: Write Mode - Create Buffer"
 cleanup_buffer "*test-buffer*"
@@ -739,6 +745,59 @@ if should_run_test "socket"; then
   fi
 fi
 
+section "Test 30: Socket Name CLI Flag"
+if should_run_test "socket"; then
+  if [ "$LIST_TESTS" = true ]; then
+    echo "  [socket] Socket name -s flag"
+  else
+    # Use -s server (default socket name) with emacsclient fallback to verify
+    # the flag plumbing works end-to-end
+    cleanup_buffer "*test-socket-name-flag*"
+    echo "socket name flag test" | MXP_NO_SOCKET=1 $SCRIPT -s server "*test-socket-name-flag*" &>/dev/null
+    output=$(MXP_NO_SOCKET=1 $SCRIPT -s server --from "*test-socket-name-flag*" 2>/dev/null)
+
+    if [[ "$output" == *"socket name flag test"* ]]; then
+      pass "Write/read round-trip with -s flag works"
+    else
+      fail "Socket name -s flag failed: got '$output'"
+    fi
+  fi
+fi
+
+section "Test 31: Socket Name Env Var"
+if should_run_test "socket"; then
+  if [ "$LIST_TESTS" = true ]; then
+    echo "  [socket] EMACS_SOCKET_NAME env var"
+  else
+    cleanup_buffer "*test-socket-name-env*"
+    echo "socket name env test" | MXP_NO_SOCKET=1 EMACS_SOCKET_NAME=server $SCRIPT "*test-socket-name-env*" &>/dev/null
+    output=$(MXP_NO_SOCKET=1 EMACS_SOCKET_NAME=server $SCRIPT --from "*test-socket-name-env*" 2>/dev/null)
+
+    if [[ "$output" == *"socket name env test"* ]]; then
+      pass "Write/read round-trip with EMACS_SOCKET_NAME env var works"
+    else
+      fail "EMACS_SOCKET_NAME env var failed: got '$output'"
+    fi
+  fi
+fi
+
+section "Test 32: Socket Name --socket-name Long Flag"
+if should_run_test "socket"; then
+  if [ "$LIST_TESTS" = true ]; then
+    echo "  [socket] Socket name --socket-name long flag"
+  else
+    cleanup_buffer "*test-socket-name-long*"
+    echo "long flag test" | MXP_NO_SOCKET=1 $SCRIPT --socket-name server "*test-socket-name-long*" &>/dev/null
+    output=$(MXP_NO_SOCKET=1 $SCRIPT --socket-name server --from "*test-socket-name-long*" 2>/dev/null)
+
+    if [[ "$output" == *"long flag test"* ]]; then
+      pass "Write/read round-trip with --socket-name flag works"
+    else
+      fail "Socket name --socket-name long flag failed: got '$output'"
+    fi
+  fi
+fi
+
 # Summary
 section "Test Summary"
 echo ""