A shell utility to run multiple independent Slack instances on Linux, each with its own configuration directory. Useful for logging into different workspaces without mixing data.

Readme.md

Virtual Slack Manager

A shell utility to run multiple independent Slack instances on Linux, each with its own configuration directory. Useful for logging into different workspaces without mixing data.

Features

virtual-slack.sh create <N> → creates a new Slack instance (Slack N) with its own config (~/.config-N)

virtual-slack.sh remove <N> → fully removes the instance and its config

virtual-slack.sh make-default <N> → temporarily make Slack N handle slack:// deep links (needed for browser login)

virtual-slack.sh restore-default → restore the original Slack as the default deep link handler

Notes

Each instance launches separately and can run side-by-side.

Browser links (http/https) always use your normal browser profile.

Slack OAuth login via browser can be routed to any instance by switching the deep-link handler.

virtual-slack.sh

#!/bin/bash
set -euo pipefail

# virtual-slack: Manage Slack variants with separate config dirs and deep-link routing
#
# Usage:
#   virtual-slack create <number>
#   virtual-slack remove <number>
#   virtual-slack make-default <number>   # make this variant handle slack:// links
#   virtual-slack restore-default         # restore original Slack as handler

if command -v slack >/dev/null 2>&1; then
  _SLACK_BIN="$(command -v slack)"
  SRC_BIN="$(readlink -f "$_SLACK_BIN")"
else
  SRC_BIN="/usr/lib/slack/slack"
fi
APP_DIR="$HOME/.local/share/applications"
LOCAL_SLACK_DESKTOP="$APP_DIR/slack.desktop"

require_src_bin() {
  if [ ! -x "$SRC_BIN" ]; then
    echo "Slack binary not found. Expected at: $SRC_BIN"
    echo "Adjust SRC_BIN in this script to your system path."
    exit 1
  fi
}

require_variant_number() {
  local num="$1"
  if [[ ! "$num" =~ ^[0-9]+$ ]]; then
    echo "Error: variant number must be numeric."
    exit 1
  fi
}

write_local_slack_desktop_variant() {
  local num="$1"
  local variant_root="$HOME/.local/share/virtual-slack-$num"
  local url_launcher="$variant_root/open-slack-$num-url.sh"

  cat > "$LOCAL_SLACK_DESKTOP" <<EOF
[Desktop Entry]
Name=Slack
StartupWMClass=browser-windox
Comment=Slack Desktop
GenericName=Slack Client for Linux
Exec=$url_launcher %U
Icon=slack
Type=Application
StartupNotify=true
Categories=GNOME;GTK;Network;InstantMessaging;
MimeType=x-scheme-handler/slack;
EOF
}

write_local_slack_desktop_original() {
  cat > "$LOCAL_SLACK_DESKTOP" <<EOF
[Desktop Entry]
Name=Slack
StartupWMClass=Slack
Comment=Slack Desktop
GenericName=Slack Client for Linux
Exec=/usr/bin/slack --gtk-version=3 -s %U
Icon=slack
Type=Application
StartupNotify=true
Categories=GNOME;GTK;Network;InstantMessaging;
MimeType=x-scheme-handler/slack;
EOF
}

set_mime_default() {
  local desktop_file="$1"
  local mime_file="$2"
  local all_desktops
  local ordered

  mkdir -p "$(dirname "$mime_file")"
  touch "$mime_file"

  all_desktops="${desktop_file};slack.desktop;slack-2.desktop;slack-3.desktop;"
  ordered="$(printf '%s' "$all_desktops" | awk -F';' '
    BEGIN { out="" }
    {
      for (i = 1; i <= NF; i++) {
        if ($i != "" && !seen[$i]++) {
          out = out $i ";"
        }
      }
    }
    END { printf "%s", out }
  ')"

  if ! grep -q '^\[Default Applications\]' "$mime_file"; then
    printf '
[Default Applications]
' >> "$mime_file"
  fi

  if grep -q '^x-scheme-handler/slack=' "$mime_file"; then
    sed -i "s|^x-scheme-handler/slack=.*|x-scheme-handler/slack=${desktop_file};|" "$mime_file"
  else
    awk -v d="$desktop_file" '
      BEGIN { done=0 }
      { print }
      /^\[Default Applications\]$/ && !done {
        print "x-scheme-handler/slack=" d ";"
        done=1
      }
      END {
        if (!done) {
          print "[Default Applications]"
          print "x-scheme-handler/slack=" d ";"
        }
      }
    ' "$mime_file" > "${mime_file}.tmp" && mv "${mime_file}.tmp" "$mime_file"
  fi

  if ! grep -q '^\[Added Associations\]' "$mime_file"; then
    printf '\n[Added Associations]\n' >> "$mime_file"
  fi

  if grep -q '^x-scheme-handler/slack=' "$mime_file"; then
    awk -v d="$desktop_file" -v o="$ordered" '
      BEGIN { in_default=0; in_added=0 }
      /^\[Default Applications\]$/ { in_default=1; in_added=0; print; next }
      /^\[Added Associations\]$/ { in_default=0; in_added=1; print; next }
      /^\[/ { in_default=0; in_added=0; print; next }
      in_default && /^x-scheme-handler\/slack=/ { print "x-scheme-handler/slack=" d ";"; next }
      in_added && /^x-scheme-handler\/slack=/ { print "x-scheme-handler/slack=" o; next }
      { print }
    ' "$mime_file" > "${mime_file}.tmp" && mv "${mime_file}.tmp" "$mime_file"
  else
    printf '\n[Default Applications]\nx-scheme-handler/slack=%s;\n' "$desktop_file" >> "$mime_file"
    printf '\n[Added Associations]\nx-scheme-handler/slack=%s\n' "$ordered" >> "$mime_file"
  fi
}

create_slack() {
  NUM="$1"
  require_variant_number "$NUM"
  require_src_bin
  DST_BIN_DIR="$(dirname "$SRC_BIN")"
  DST_BIN="$DST_BIN_DIR/slack-$NUM"
  VAR_ROOT="$HOME/.local/share/virtual-slack-$NUM"
  VAR_BIN="$VAR_ROOT/bin"
  LAUNCHER="$VAR_ROOT/launch-slack-$NUM.sh"
  URL_LAUNCHER="$VAR_ROOT/open-slack-$NUM-url.sh"
  CONFIG_DIR="$HOME/.config-$NUM"
  DESKTOP_FILE="$APP_DIR/slack-$NUM.desktop"

  echo "[1/6] Copying Slack binary to $DST_BIN ..."
  sudo cp -rp "$SRC_BIN" "$DST_BIN"

  echo "[2/6] Patching window class string ..."
  if sudo grep -aq $'\x00browser-window\x00' "$DST_BIN"; then
    sudo sed -i 's/\x00browser-window\x00/\x00browser-windox\x00/g' "$DST_BIN"
  else
    echo "Note: 'browser-window' marker not found; skipping patch."
  fi

  echo "[3/6] Creating per-variant shims ..."
  mkdir -p "$VAR_BIN"

  SYS_XDG_OPEN="$(command -v xdg-open || true)"
  SYS_GIO="$(command -v gio || true)"
  [ -z "$SYS_XDG_OPEN" ] && SYS_XDG_OPEN="/usr/bin/xdg-open"
  [ -z "$SYS_GIO" ] && SYS_GIO="/usr/bin/gio"

  cat > "$VAR_BIN/xdg-open" <<'EOF'
#!/bin/sh
# Ensure child apps (browsers etc.) use normal user config, not the virtual Slack's config.
unset XDG_CONFIG_HOME
exec /usr/bin/xdg-open "$@"
EOF
  chmod +x "$VAR_BIN/xdg-open"

  cat > "$VAR_BIN/gio" <<'EOF'
#!/bin/sh
unset XDG_CONFIG_HOME
exec /usr/bin/gio "$@"
EOF
  chmod +x "$VAR_BIN/gio"

  [ "$SYS_XDG_OPEN" != "/usr/bin/xdg-open" ] && sed -i "s|/usr/bin/xdg-open|$SYS_XDG_OPEN|g" "$VAR_BIN/xdg-open"
  [ "$SYS_GIO" != "/usr/bin/gio" ] && sed -i "s|/usr/bin/gio|$SYS_GIO|g" "$VAR_BIN/gio"

  echo "[4/6] Creating launcher ..."
  mkdir -p "$VAR_ROOT"
  cat > "$LAUNCHER" <<EOF
#!/bin/sh
export PATH="$VAR_BIN:\$PATH"
export XDG_CONFIG_HOME="$CONFIG_DIR"
exec "$DST_BIN" --gtk-version=3 -s "\$@"
EOF
  chmod +x "$LAUNCHER"

  cat > "$URL_LAUNCHER" <<EOF
#!/bin/sh
URL="\${1:-}"

# Avoid the primary Slack instance hijacking slack:// deep links via single-instance IPC.
# Kill only the original Slack launcher path, not this variant.
for slack_cmd in "$SRC_BIN" /usr/bin/slack; do
  [ -n "\$slack_cmd" ] || continue
  pkill -f "^\$slack_cmd( |$)" >/dev/null 2>&1 || true
done

for _ in 1 2 3 4 5 6 7 8 9 10; do
  still_running=0
  for slack_cmd in "$SRC_BIN" /usr/bin/slack; do
    [ -n "\$slack_cmd" ] || continue
    if pgrep -f "^\$slack_cmd( |$)" >/dev/null 2>&1; then
      still_running=1
      break
    fi
  done
  [ "\$still_running" -eq 0 ] && break
  sleep 0.2
done

exec "$LAUNCHER" "\$URL"
EOF
  chmod +x "$URL_LAUNCHER"

  echo "[5/6] Writing desktop entry ..."
  mkdir -p "$APP_DIR"
  cat > "$DESKTOP_FILE" <<EOF
[Desktop Entry]
Name=Slack $NUM
Comment=Slack using alternate config directory $NUM
Exec=$URL_LAUNCHER %u
Icon=slack
Type=Application
Terminal=false
Categories=Network;Chat;
StartupWMClass=browser-windox
MimeType=x-scheme-handler/slack;
EOF

  echo "[6/6] Refreshing menus ..."
  command -v update-desktop-database >/dev/null 2>&1 && update-desktop-database "$APP_DIR" || true
  command -v kbuildsycoca5 >/dev/null 2>&1 && kbuildsycoca5 || true

  echo "✅ Slack $NUM installed (virtual-slack-$NUM)."
  echo ""
  echo "Tip: To login into workspaces using this slack instance,"
  echo "     you need to make this instance to be able to capture"
  echo "     slack:// links by runnning:"
  echo ""
  echo "     virtual-slack make-default $NUM"
  echo ""
  echo "     Once you have logged in successfully, you need to restore the"
  echo "     original slack handler by running:"
  echo ""
  echo "     virtual-slack restore-default"
  echo ""
}

remove_slack() {
  NUM="$1"
  require_variant_number "$NUM"
  require_src_bin
  DST_BIN_DIR="$(dirname "$SRC_BIN")"
  DST_BIN="$DST_BIN_DIR/slack-$NUM"
  VAR_ROOT="$HOME/.local/share/virtual-slack-$NUM"
  DESKTOP_FILE="$APP_DIR/slack-$NUM.desktop"
  CONFIG_DIR="$HOME/.config-$NUM"

  echo "[1/4] Removing cloned binary..."
  [ -f "$DST_BIN" ] && sudo rm -f "$DST_BIN" && echo "Deleted $DST_BIN" || echo "Not found: $DST_BIN"

  echo "[2/4] Removing virtual-slack runtime dir..."
  [ -d "$VAR_ROOT" ] && rm -rf "$VAR_ROOT" && echo "Deleted $VAR_ROOT" || echo "Not found: $VAR_ROOT"

  echo "[3/4] Removing desktop entry..."
  [ -f "$DESKTOP_FILE" ] && rm -f "$DESKTOP_FILE" && echo "Deleted $DESKTOP_FILE" || echo "Not found: $DESKTOP_FILE"

  echo "[4/4] Removing config dir..."
  [ -d "$CONFIG_DIR" ] && rm -rf "$CONFIG_DIR" && echo "Deleted $CONFIG_DIR" || echo "Not found: $CONFIG_DIR"

  command -v update-desktop-database >/dev/null 2>&1 && update-desktop-database "$APP_DIR" || true
  command -v kbuildsycoca5 >/dev/null 2>&1 && kbuildsycoca5 || true

  echo "✅ Slack $NUM fully removed."
}

make_default() {
  NUM="$1"
  require_variant_number "$NUM"
  DESKTOP_FILE="slack-$NUM.desktop"
  FULL_DESKTOP_FILE="$APP_DIR/$DESKTOP_FILE"

  if [ ! -f "$FULL_DESKTOP_FILE" ]; then
    echo "Error: desktop file not found: $FULL_DESKTOP_FILE"
    exit 1
  fi

  echo "Setting $DESKTOP_FILE as default handler for slack:// ..."
  xdg-mime default "$DESKTOP_FILE" x-scheme-handler/slack

  # Force-write common user mimeapps locations used by gio/desktop environments.
  set_mime_default "$DESKTOP_FILE" "$HOME/.config/mimeapps.list"
  set_mime_default "$DESKTOP_FILE" "$HOME/.local/share/applications/mimeapps.list"
  command -v gio >/dev/null 2>&1 && gio mime x-scheme-handler/slack "$DESKTOP_FILE" >/dev/null || true
  write_local_slack_desktop_variant "$NUM"

  # Some desktop/browser combinations consult xdg-settings for URL handlers.
  command -v xdg-settings >/dev/null 2>&1 && xdg-settings set default-url-scheme-handler slack "$DESKTOP_FILE" || true

  update_desktop_cache

  echo "Current handler checks:"
  echo "  xdg-mime:     $(xdg-mime query default x-scheme-handler/slack 2>/dev/null || echo unknown)"
  echo "  xdg-settings: $(xdg-settings get default-url-scheme-handler slack 2>/dev/null || echo unknown)"

  echo "✅ Now, browser OAuth deep links (slack://) should open in Slack $NUM."
  echo "If they still open another instance, that is usually Slack single-instance routing from an already running process."
}

restore_default() {
  echo "Restoring original Slack as default handler for slack:// ..."
  xdg-mime default slack.desktop x-scheme-handler/slack
  set_mime_default "slack.desktop" "$HOME/.config/mimeapps.list"
  set_mime_default "slack.desktop" "$HOME/.local/share/applications/mimeapps.list"
  command -v gio >/dev/null 2>&1 && gio mime x-scheme-handler/slack slack.desktop >/dev/null || true
  write_local_slack_desktop_original
  command -v xdg-settings >/dev/null 2>&1 && xdg-settings set default-url-scheme-handler slack "slack.desktop" || true
  update_desktop_cache
  echo "✅ Restored original Slack as the handler."
}

update_desktop_cache() {
  command -v update-desktop-database >/dev/null 2>&1 && update-desktop-database "$APP_DIR" || true
  command -v kbuildsycoca5 >/dev/null 2>&1 && kbuildsycoca5 || true
}

# --- Main ---
if [ $# -lt 1 ]; then
  echo "Usage: $0 {create|remove|make-default|restore-default} [number]"
  exit 1
fi

CMD="$1"
case "$CMD" in
  create)
    [ $# -lt 2 ] && { echo "Usage: $0 create <number>"; exit 1; }
    create_slack "$2"
    ;;
  remove)
    [ $# -lt 2 ] && { echo "Usage: $0 remove <number>"; exit 1; }
    remove_slack "$2"
    ;;
  make-default)
    [ $# -lt 2 ] && { echo "Usage: $0 make-default <number>"; exit 1; }
    make_default "$2"
    ;;
  restore-default)
    restore_default
    ;;
  *)
    echo "Unknown command: $CMD"
    echo "Usage: $0 {create|remove|make-default|restore-default} [number]"
    exit 1
    ;;
esac