[question] X11 forwarding

[noamgot]

question

I intend to work with herdr on a remote machine via SSH
does it support X11 forwarding somehow?

I tested 2 cases for now:

1. connect with ssh -Y and then open herdr
2. connect (from my local machine) with herdr --remote ssh://...
   in both cases I tried running xeyes, unsuccesfully...

context

No response

[noamgot]

I came out with this workaround:

# --- Herdr X11 Display Syncing ---

# 1. Outside herdr: Save the active SSH display pointer
if [ -n "$SSH_TTY" ] && [ -z "$HERDR_ENV" ]; then
    echo "export DISPLAY=\"$DISPLAY\"" > ~/.herdr_x11_env
fi

# 2. Inside herdr: Read the active SSH display pointer
if [ "$HERDR_ENV" = "1" ]; then
    if [ -f ~/.herdr_x11_env ]; then
        source ~/.herdr_x11_env
    fi
fi

it should work if you first connet with ssh -Y; not sure if it works if you use herdr --remote ssh://user@host

@ogulcancelik don't know if it's a bug, but I think it would be nice to handle it internally (not with this workaround) - personally, I want to be able to open GUI apps, as well as use clipboard realted zsh plugins (such as copypath / copybuffer etc.)

[ampatzid]

Does this also solve the copy to clipboard issue?

[noamgot]

for me it works (i.e., I can copy text to clipboard), but I believe it depends on some other x11 forwarding settings.
I think it's safe to say that if without herdr copying to clipboard works, with this configuration it should work also inside herdr.
do notice that if you re-attach herdr the DISPLAY env-var might be outdated. in this case just restart the shell (e.g soucre ~/.zshrc)

[colinmollenhour]

The @noamgot solution works for ssh->herdr but not for herder --remote. Here is one that works for herdr --remote (and any other SSH connection probably, it's not specific to herdr).

Usage:

1. Add it to your ~/.bashrc or equivalent (and source ~/.bashrc in your current shell)
2. Run fixdisplay to update your env whenever it's broken
3. Then run your X app

This should still be a first-party feature ideally since if you have an agent already running, running fixdisplay will not update the env for the agent. I'm not sure how to update the agent's env, though, so it may not be possible... As a fallback maybe it should be advised in the user-level AGENTS.md.

Anyway, the fix:

# --- X11 over SSH: discover / refresh DISPLAY ---
# Call `fixdisplay` after re-SSH / when xcalc says "Can't open display".
# Also auto-runs for interactive shells (and prefers tmux showenv when in tmux).

# Find SSH X11 forward: localhost listens on 6000+N for display :N
_x11_find_display() {
  local ports port n
  # Newest connection usually gets the highest display number
  ports=$(ss -ltn 2>/dev/null | awk '
    $4 ~ /^127\.0\.0\.1:60[0-9][0-9]$/ {
      split($4, a, ":"); print a[2]
    }' | sort -n)
  [ -z "$ports" ] && return 1

  # Prefer highest open port that has an xauth cookie
  for port in $(echo "$ports" | tac); do
    n=$((port - 6000))
    if xauth list 2>/dev/null | grep -qE "[:/]${n}( |$)"; then
      printf 'localhost:%s.0' "$n"
      return 0
    fi
  done

  # Fall back: highest open X11-forward port
  port=$(echo "$ports" | tail -1)
  printf 'localhost:%s.0' "$((port - 6000))"
}

# Persist for other shells / later reattach in this host session
_x11_save_display() {
  local d="${1:-$DISPLAY}"
  [ -n "$d" ] || return 1
  umask 077
  {
    printf 'export DISPLAY=%q\n' "$d"
    # Only set XAUTHORITY if you use a non-default path
    [ -n "${XAUTHORITY:-}" ] && printf 'export XAUTHORITY=%q\n' "$XAUTHORITY"
  } > "$HOME/.xdisplay"
}

# Call this after re-SSH / when xcalc says "Can't open display"
fixdisplay() {
  local d
  if [[ -n ${TMUX:-} ]]; then
    # Prefer tmux's updated env when available
    if eval "$(tmux showenv -s DISPLAY 2>/dev/null)"; then
      _x11_save_display
      echo "DISPLAY=$DISPLAY (from tmux)"
      return 0
    fi
  fi
  d=$(_x11_find_display) || {
    echo "fixdisplay: no SSH X11 listener on 127.0.0.1:60xx" >&2
    return 1
  }
  export DISPLAY="$d"
  _x11_save_display "$d"
  echo "DISPLAY=$DISPLAY"
}

# Interactive shells: refresh if missing/wrong-looking
if [[ $- == *i* ]]; then
  if [[ -n ${TMUX:-} ]]; then
    eval "$(tmux showenv -s DISPLAY 2>/dev/null)" || true
  fi
  # If sshd/tmux already set a sensible localhost display, keep it
  if [[ "${DISPLAY:-}" == localhost:* || "${DISPLAY:-}" == 127.0.0.1:* ]]; then
    _x11_save_display
  else
    # Overwritten (e.g. LAN IP:11.0) or unset → rediscover
    if d=$(_x11_find_display); then
      export DISPLAY="$d"
      _x11_save_display "$d"
    elif [[ -f "$HOME/.xdisplay" ]]; then
      # No live tunnel right now; last-known (may be stale)
      # shellcheck disable=SC1090
      source "$HOME/.xdisplay"
    fi
  fi
fi
# --- end X11 over SSH ---