1# Configuration
2
3NeferWL reads `~/.config/neferwl/config` (or `$XDG_CONFIG_HOME/neferwl/config`). Changes apply when you save, except `startup` and `xwayland`, which apply at the next start.
4
5```sh
6neferwl --config <path>            # use another file
7neferwl validate-config [path]     # check a file
8```
9
10Missing keys use defaults. Empty keyboard values use the system setting. No startup commands or named workspaces are configured by default. The log lists changed keys after a reload.
11
12## Format
13
14- One `key = value` per line. `#` starts a comment.
15- Lists are comma-separated; booleans are `on` / `off`.
16- An invalid line logs a warning and keeps the default. If a key appears twice, the last one wins.
17
18See [examples/config](../examples/config) for every key with its default.
19
20## Keys
21
22| Key | Default | Meaning |
23|---|---|---|
24| `keyboard.layout`, `.variant`, `.options` | empty | xkb names, e.g. `fr`, `caps:escape` |
25| `keyboard.repeat-rate` / `.repeat-delay` | `25` / `600` | Repeats per second / delay in ms |
26| `keyboard.cmd` | `super` | Modifier meant by `cmd` in binds: `super`, `alt` or `ctrl` |
27| `terminal` | `$TERMINAL` or `foot` | Terminal command |
28| `terminal.auto-open` | `first` | Open a terminal on the first workspace (`first`), on every empty one (`all`), or never (`off`) |
29| `startup` | none | Commands run at session start, separated by `;` |
30| `xwayland` | `xwayland-satellite` | X11 support; `off` disables it |
31| `background` | `#111111` | Background color |
32| `border.radius` | `0` | Corner radius in logical pixels, `0` to `64`; floats always, tiles only with gaps |
33| `border.width` | `2` | Border width in pixels; `0` hides borders |
34| `border.active` / `.inactive` | `#808080` / `#111111` | Border colors of the focused / other windows |
35| `floating.dim` | `0.3` | Darkening behind floating windows and the overview, 0 to 1 |
36| `layout.gaps` | `0` | Space between windows |
37| `layout.max-columns` | `2` | Columns that share the screen |
38| `layout.overflow` | `cascade` | What happens past `max-columns`: [`cascade`](#cascade) into bands below, `scroll` right, or `fixed` spiral split |
39| `layout.<output>.max-columns`, `.overflow` | layout values | Per-output layout |
40| `stash.width` | `80` | Width of the selected [stashed](#stash) window, in % of the screen (10–90) |
41| `stash.gap` | `2` | Gap around the selected stashed window, in % (0–10) |
42| `stash.dim` | `0.5` | Darkening of the stash neighbors, 0 to 1 |
43| `stash.capture` | `on` | A window opened while the stash shows joins the stash |
44| `stash.spawn-terminal` | `on` | `toggle-stash-visible` on an empty stash opens `terminal` in it |
45| `touchpad.natural-scroll` | `off` | Content follows the fingers |
46| `touchpad.tap` | `on` | Tap to click |
47| `touchpad.accel-speed` | `0` | Pointer speed, `-1` to `1` |
48| `touchpad.accel-profile` | `adaptive` | `adaptive` or `flat` |
49| `touchpad.left-handed` | `off` | Swap left and right buttons |
50| `touchpad.scroll-factor` | `1` | Scroll speed multiplier, up to `10` |
51| `mouse.natural-scroll`, `.accel-speed`, `.accel-profile`, `.left-handed` | as touchpad | Same, for mice, trackballs and trackpoints |
52| `cursor.hide-after` | `5s` | Hide the cursor after this long without motion, or `off` |
53| `animations` | `off` | **Experimental.** Animate layout changes and make swipes follow the fingers |
54| `animations.speed` | `normal` | `slow`, `normal`, `fast`, or a factor from `0.1` to `10` |
55| `focus.follow-move` | `off` | Follow a column moved to another workspace |
56| `focus.position-hint` | `on` | Show workspace/band dots near the output bottom for 600ms after a position change, then fade for 150ms (no fade with animations off); hidden in overview, fullscreen and session lock; never captured |
57| `focus.flash` | `on` | Briefly draw an inner border, inside the window border, on the window, column or output an action changed |
58| `focus.flash-width` | `2` | Flash border width in logical pixels, `1` to `8` |
59| `focus.flash-opacity` | `0.6` | Starting opacity of the flash, `0.1` to `1` |
60| `focus.flash-duration` | `200ms` | Fade duration, `50ms` to `1s`; not scaled by `animations.speed` |
61| `focus.flash-color` | `border.active` | Flash color `#rrggbb`; empty uses `border.active` |
62| `hint.enable` | `off` | Turn on the experimental [hint mode](#hint-mode) (restart required) |
63| `hint.detector` | `nefer-hints` | The [hint mode](#hint-mode) detector binary: a path, or a name looked up in `PATH` (restart required) |
64| `hint.model` | `$XDG_DATA_HOME/nefer-hints/models` | Directory of the detector's model files; `~/.local/share/nefer-hints/models` when `XDG_DATA_HOME` is unset; a leading `~/` is expanded (restart required) |
65| `hint.threshold` | model default | Optional minimum detection score override, 0.01 to 0.99; unset or empty uses the model’s own threshold (`model.json`), else the runner default. Lower finds more targets and more false ones (restart required) |
66| `hint.capture` | `off` | Show hint labels in captures requested by Wayland clients (screenshots, screencasts); the compositor's own hint scans never see them; applies on reload |
67| `hint.size` | `auto` | Label text size in logical pixels (6 to 72), or `auto` for screen pixel density |
68| `hint.background` | empty | Label background (`#rrggbb`); empty uses `border.active` |
69| `hint.foreground` | empty | Label text (`#rrggbb`); empty chooses a contrasting colour |
70| `workspace.<name>.monitor` | focused output | Home monitor of a named workspace |
71| `workspace.<name>.size` | `inherit` | [Smaller viewport](#workspace-size), e.g. `1920x1080` |
72| `workspace.<name>.max-columns`, `.overflow` | output values | Per-workspace layout |
73| `workspace.<name>.column.<N>` | none | Column slot: `<cells>, <command>` |
74| `rule.<name>.*` | none | [Window rules](#window-rules) |
75| `output.<name>` | `preferred` | `WxH`, `WxH@Hz`, `preferred` or `off` |
76| `output.<name>.scale` | `1` | 1 to 4, e.g. `1.5` or `4/3` |
77| `output.<name>.transform` | `normal` | `90`, `180`, `270`, `flipped`, `flipped-90`, … |
78| `output.<name>.primary` | `off` | Focused at startup |
79| `output.<name>.right-of`, `.left-of`, `.above`, `.below`, `.offset` | automatic | [Output placement](#output-placement) |
80| `output.<name>.hdr` | `off` | [HDR](#hdr) on capable displays |
81| `output.<name>.sdr-brightness` | `203` | Brightness of SDR content in HDR, in nits (80–1000) |
82| `render.direct-scanout` | `on` | Send fullscreen windows straight to the display |
83| `render.tearing` | `on` | Allow tearing for fullscreen games |
84| `render.vrr` | `on` | Variable refresh rate for fullscreen windows |
85| `render.vrr-flip-gap` | `1ms` | See [Performance](performance.md#vrr) |
86| `performance.realtime` | `on` | Real-time scheduling |
87| `log.level` / `log.debug` | `info` / empty | Log level / debug categories or `all` |
88| `bind.<keys>` | see [Default binds](#default-binds) | [Binds](#binds) |
89
90With `layout.gaps = 0`, borders are tmux-style lines between tiles. With gaps, every tile gets a full border, even alone. `border.radius` rounds floating windows always and tiles with gaps; fullscreen windows, popups and layers stay square.
91
92`<output>` is a connector such as `DP-2`, or a monitor key (`make model serial`).
93
94The position hint follows actual workspace/band changes and monitor focus, regardless
95of input method. It lists all ext-workspace entries in monitor order: numbered
96workspaces (including the empty spare), then configured hidden named workspaces,
97even when empty. Cascade workspaces use top-aligned band columns; scroll/fixed
98workspaces use one vertical workspace column. Large lists show at most 16 entries
99with the active entry kept visible; band rows are capped at 16.
100
101The focus flash marks the window, column or output an action changes with a brief
102inner border. When a flash-triggering action crosses screens, it marks the whole
103destination output, even if that output has no windows. Same-screen workspace
104switches and mouse focus do not trigger a flash.
105It runs when `animations = on`.
106
107## Automatic terminal
108
109The command comes from `terminal`, then `$TERMINAL`, then `foot`.
110
111| `terminal.auto-open` | Behaviour |
112| --- | --- |
113| `first` | Open once on the initial numbered workspace |
114| `all` | Open on each visible empty workspace without predefined slots |
115| `off` | Do not open automatically |
116
117`--no-terminal` disables automatic opening for one run; `spawn-terminal` still works. Launched programs inherit `$SHELL`, `$EDITOR` and `$VISUAL`.
118
119## Per-output defaults
120
121Per-output defaults (replace `<name>` with a connector such as `DP-1`):
122
123```text
124output.<name> = preferred
125output.<name>.scale = 1
126output.<name>.transform = normal
127output.<name>.primary = off
128output.<name>.offset = 0
129output.<name>.hdr = off
130output.<name>.sdr-brightness = 203
131```
132
133Outputs are arranged automatically unless `.right-of`, `.left-of`, `.above` or `.below` is set. Per-output layouts inherit `layout.*`; named workspaces inherit their output's layout and size, use the focused output unless `.monitor` is set, and have no predefined columns. Media keys have no default bindings.
134
135## Window rules
136
137Rules place an app's windows when they first open.
138
139| Key | Meaning |
140|---|---|
141| `rule.<name>.app-id` | Required. [Regular expression](https://pkg.go.dev/regexp/syntax) matching the whole app ID |
142| `rule.<name>.floating` | `on` to float, `off` to tile |
143| `rule.<name>.workspace` | Workspace number or name |
144| `rule.<name>.monitor` | Output |
145| `rule.<name>.width` | Column width in [cells](#column-widths), 1 to 16 |
146
147```ini
148rule.games.app-id = steam_app_.*
149rule.games.workspace = 3
150rule.chat.app-id = discord|org\.telegram\..*
151rule.chat.workspace = chat
152rule.chat.width = 1
153rule.calc.app-id = org\.gnome\.Calculator
154rule.calc.floating = on
155```
156
157- Every matching rule applies, in file order; later rules win.
158- A rule never moves your focus or view.
159- To find an app ID: `neferwl state | jq '.windows[].app_id'`.
160
161## Output placement
162
163By default, outputs sit left to right in config order. Place one against another, and use `offset` (logical pixels) to align the edges:
164
165```ini
166output.DP-2.right-of = DP-1
167output.DP-2.offset = 360    # DP-2 starts 360 px lower than DP-1
168```
169
170```
171┌────────────┐
172│            │┌─────────┐
173│    DP-1    ││  DP-2   │
174│ 2560x1440  ││1920x1080│
175│            │└─────────┘
176└────────────┘
177```
178
179`offset` moves down for `right-of`/`left-of`, and right for `above`/`below`. kanshi, wdisplays and wlr-randr override these settings until the next reload.
180
181## Workspace size
182
183`workspace.<name>.size` gives a named workspace a smaller centered viewport, for example to present at 1080p on a 4K screen:
184
185```ini
186workspace.presentation.size = 1920x1080
187bind.cmd+p = workspace presentation
188```
189
190## Touchpad
191
192| Gesture | Action |
193|---|---|
194| Three fingers left/right | Scroll columns (switch workspace in cascade) |
195| Three fingers up/down | Switch workspace (scroll bands in cascade) |
196| Four fingers up | Open the overview, or hide the stash |
197| Four fingers down | Close the overview, or show/hide the stash |
198
199A swipe moves one step at most. Other gestures (pinch, hold, two-finger scroll) go to the app under the pointer.
200
201## HDR
202
203`output.<name>.hdr = on` sends HDR10 to displays that support it. If the display, driver or GPU cannot, NeferWL falls back to SDR and logs why. NVIDIA is not supported yet.
204
205- HDR-aware apps (games, browsers, video players) can show HDR content. Some need HDR turned on in their own settings. X11 apps stay SDR.
206- The desktop stays SDR, shown at `sdr-brightness` nits.
207- Fullscreen HDR windows go straight to the display.
208- Screenshots and captures are SDR (tone-mapped).
209- If NeferWL crashes, the next compositor may show distorted colours until it sets its own colour pipeline.
210
211## Binds
212
213`bind.<keys> = <action>`. Modifiers: `cmd` (see `keyboard.cmd`), `shift`, `ctrl`, `alt`, `super`.
214
215- Keys are what your layout prints: `cmd+é` on AZERTY. Write `=`, `#` and space by name: `cmd+equal`, `cmd+numbersign`, `cmd+space`.
216- `code:N` is a physical key, the same on every layout: `code:2` to `code:10` are the digits 1 to 9.
217- Other keys use their xkb name (`wev` shows it).
218- `none` removes a default bind.
219- `spawn <command>` runs a program without a shell. See [Running commands](desktop.md#running-commands).
220- Holding a move bind repeats it: focus, move, resize and workspace steps, first after 250 ms, then 8 times a second. Toggles, spawns and closes run once. The overview's arrows and `h/j/k/l` repeat the same way.
221
222```ini
223bind.XF86AudioRaiseVolume = spawn wpctl set-volume -l 1.0 @DEFAULT_AUDIO_SINK@ 5%+
224bind.XF86AudioLowerVolume = spawn wpctl set-volume @DEFAULT_AUDIO_SINK@ 5%-
225bind.XF86AudioMute = spawn wpctl set-mute @DEFAULT_AUDIO_SINK@ toggle
226bind.XF86MonBrightnessUp = spawn brightnessctl set +5%
227bind.XF86MonBrightnessDown = spawn brightnessctl set 5%-
228```
229
230### Actions
231
232| Action | Effect |
233|---|---|
234| `spawn <command>` | Run a program |
235| `spawn-terminal` | Run `terminal` |
236| `stash <command>` | Run a program and open its window in the [stash](#stash) |
237| `close-window` | Close the focused window |
238| `toggle-fullscreen` | Fullscreen the focused window. Nothing shows above it except its own dialogs |
239| `toggle-floating` | Make the focused window [float](#free-floating-windows), or put it back in its column |
240| `toggle-window-stash` | Move the focused window to the [stash](#stash), or back to its column |
241| `toggle-stash-visible` | Show or hide the stash |
242| `toggle-overview` | Open or close the [overview](#overview) |
243| `hint` | Label the clickable elements on the focused screen, then click the one you type ([hint mode](#hint-mode)) |
244| `switch-column-next` / `-prev` | Switch to the previously used column. Hold `cmd` and press again to go further back |
245| `maximize-column` | Toggle full width for the focused column |
246| `cycle-column-width` | Grow the focused column by one [cell](#column-widths), then back to equal widths |
247| `set-column-width <+N\|-N>` | Widen or narrow the focused column by N cells |
248| `set-window-height <+N%\|-N%>` | Change the focused window's share of its column |
249| `focus-column-left/right` | Focus the neighbor column, then the neighbor monitor |
250| `focus-window-up/down` | Focus the neighbor window in the column, then the neighbor workspace (band in cascade) |
251| `move-column-left/right` | Move the focused column, then to the neighbor monitor |
252| `move-window-up/down` | Move the focused window in its column |
253| `consume-or-expel-window-left/right` | Join the neighbor column, or leave the current one |
254| `focus-workspace <N>` / `-prev/-next` | Show a workspace |
255| `workspace <name>` | Show or hide a named workspace |
256| `move-column-to-workspace <N>` / `-prev/-next` | Move the focused column to a workspace |
257| `move-window-to-workspace <N>` / `-prev/-next` | Move the focused window to a workspace |
258| `move-workspace-prev/next` | Swap the workspace with its neighbor |
259| `focus-monitor-left/right/up/down` | Focus the neighbor monitor |
260| `move-workspace-to-monitor-left/right/up/down` | Move the workspace to the neighbor monitor |
261| `scale-up` / `scale-down` | Zoom the display; the scale is saved to the config |
262| `quit` | Exit NeferWL |
263
264### Default binds
265
266| Keys | Action |
267|---|---|
268| `cmd+return` | `spawn-terminal` |
269| `ctrl+cmd+space` | `spawn fuzzel` |
270| `cmd+q` | `close-window` |
271| `cmd+left/right`, `cmd+h/l` | `focus-column-left/right` |
272| `cmd+up/down`, `cmd+k/j` | `focus-window-up/down` |
273| `cmd+shift+left/right`, `cmd+shift+h/l` | `move-column-left/right` |
274| `cmd+shift+up/down`, `cmd+shift+k/j` | `move-window-up/down` |
275| `cmd+bracketleft/bracketright` | `consume-or-expel-window-left/right` |
276| `cmd+alt+left/right`, `cmd+alt+h/l` | `set-column-width -1/+1` |
277| `cmd+alt+up/down`, `cmd+alt+k/j` | `set-window-height -10%/+10%` |
278| `cmd+r` | `cycle-column-width` |
279| `cmd+f` | `maximize-column` |
280| `cmd+shift+f` | `toggle-fullscreen` |
281| `cmd+shift+space` | `toggle-floating` |
282| `cmd+s` | `toggle-stash-visible` |
283| `cmd+shift+s` | `toggle-window-stash` |
284| `cmd+o` | `toggle-overview` |
285| `cmd+tab` / `cmd+shift+tab` | `switch-column-next/prev` |
286| `cmd+1`…`9` (`code:2`…`10`) | `focus-workspace 1`…`9` |
287| `cmd+shift+1`…`9` | `move-column-to-workspace 1`…`9` |
288| `cmd+pageup/pagedown` | `focus-workspace-prev/next` |
289| `cmd+shift+pageup/pagedown` | `move-column-to-workspace-prev/next` |
290| `cmd+ctrl+arrows`, `cmd+ctrl+h/j/k/l` | `focus-monitor-*` |
291| `cmd+ctrl+shift+left/right`, `cmd+ctrl+shift+h/l` | `move-workspace-to-monitor-left/right` |
292| `cmd+ctrl+shift+up/down`, `cmd+ctrl+shift+k/j` | `move-workspace-prev/next` |
293| `cmd+code:12` / `cmd+code:13` (`-` / `=` on US) | `scale-down` / `scale-up` |
294| `ctrl+alt+backspace` | `quit` |
295
296With `keyboard.cmd = alt` or `ctrl`, the defaults that would combine `cmd` with that same modifier are dropped. Bind those actions to other keys.
297
298## Layout
299
300### Cascade
301
302The default layout. Columns sit side by side in bands of up to `max-columns`, stacked one below the other. Each band fills the screen height and keeps its columns until you move them.
303
304- Left/right focus moves within a band, then to the neighbor monitor, then to the neighbor workspace.
305- `move-column-left/right` stays in the band; at its edge the column goes to the neighbor monitor, if any.
306- Up/down moves through the windows of a column, then to the band above or below.
307- `move-window-up/down` past the column's top or bottom sends the whole column to the band above or below. It joins that band when it has room, else it gets a new band between the two.
308- A new window joins the focused band when it has room, else it gets a new band right below.
309- `cycle-column-width` in a full band makes room: the rightmost column goes to the band below (from the last column, the leftmost goes to the band above). The end of the cycle brings it back.
310- `maximize-column` gives the column a band of its own: the columns on its left go to the band above, the ones on its right to the band below. Maximizing again forms the band back.
311- A band left empty goes away. A smaller `max-columns` moves the extra columns of a band to a new band below it.
312
313### Column widths
314
315A cell is `1/max-columns` of the screen width. A column is 1 to 16 cells wide. Columns without a set width share the space equally.
316
317### Stash
318
319Each workspace has a stash: a strip of windows set aside with `toggle-window-stash`. The selected one shows centered over your columns, with its neighbors dimmed on the sides. `focus-column-left/right` or a three-finger swipe browse it. `toggle-stash-visible` or a four-finger swipe hides it.
320
321`stash <command>` runs a program and opens its window straight in the stash of the workspace you were on, selected and focused, even if you switch workspace before it appears. With `stash.spawn-terminal`, `toggle-stash-visible` or the four-finger swipe down on an empty stash does the same with `terminal`.
322
323```ini
324bind.cmd+shift+f = stash firefox
325```
326
327The window must appear within 5 seconds, otherwise it opens normally. Apps that hand a launch to an already running instance (single-instance browsers, `footclient`) open their window normally.
328
329### Free floating windows
330
331`toggle-floating` turns the focused window into a floating window that stays where you put it. On a floating window, move binds move it by 50 pixels and resize binds resize it.
332
333### Moving windows with the pointer
334
335- `cmd` + left drag moves a window. Drop it on the top or bottom of another window to stack it there, or in the middle to swap.
336- `cmd` + right drag resizes a floating window.
337- `cmd` + right drag on the line between two columns or two stacked windows resizes them.
338- `cmd` + double right-click on that line resets the lane's column widths or the column's row heights. Column widths reset when a column enters or leaves the lane.
339- `Escape` cancels the drag and restores the previous sizes.
340
341### Overview
342
343`toggle-overview` (or a four-finger swipe up) shows previews of your workspaces. Arrows, `h/j/k/l` or three-finger swipes move the selection; `Return` or a click opens it; `Escape` goes back. `close-window` and the move-to-workspace binds work on the selected preview.
344
345A workspace's stash shows as a pile of cards. Selecting the pile unfolds it into a carousel of every stashed window: a row under the workspace with `layout.overflow = cascade`, a column on its left otherwise. The selected card stays in the middle, the earlier cards before it and the later ones after it, wrapping round; a wider gap separates the newest card from the oldest. Moves along the carousel pick a card. With fewer than three cards, or on a workspace holding only stashed windows, it does not wrap round. Leaving it folds it again. Moving to another workspace selects its windows rather than a carousel that wraps round, even when its stash has the focus, so browsing workspaces never stops on one.
346
347With `layout.overflow = cascade`, workspaces sit side by side, each band of columns is a lane, and the stash sits under the lanes. Down (or fingers down on the touchpad, with natural scroll off) moves to the lane below; past the last lane it unfolds the stash. Left/right walk the cards; where the carousel does not wrap round, they go to the neighbor workspace past either end. Up leaves the stash for the last lane, at the column you came from.
348
349Otherwise, left from the first column unfolds the stash. Up/down walk the cards, the focus-workspace binds change workspace, and right goes back to the columns.
350
351## Hint mode
352
353Hint mode is experimental and off by default: set `hint.enable = on` and restart NeferWL.
354While it is off, nothing of hint mode runs or uses memory, and the `hint` bind
355logs a notice once and does nothing. A reload does not change it.
356
357`hint` labels the clickable elements (buttons, links, icons, fields) on the
358focused output. Type a label to click its target; BackSpace erases a letter,
359Escape cancels. No bind is set by default; for example `bind.cmd+g = hint`.
360
361Labels use the `border.active` colour with a contrasting text colour, and
362their size follows the screen's pixel density. Each label sits just outside
363the top-left corner of its target. The click is a plain left click.
364
365Labels are not part of screenshots and screencasts by default. With
366`hint.capture = on` they appear in the captures that Wayland clients request
367(including Exclude captures); the detector never sees them.
368The capture indicator and the position hint stay out of every capture.
369A reload applies `hint.capture` to the next frame.
370
371### Where targets come from
372
373Targets come from `nefer-hints`, a separate program that looks at the pixels of
374the whole output with a neural network and returns a box for each clickable
375element. It works the same for every app, toolkit and terminal. It sees what is
376drawn: it does not know what an element does, and it can miss or invent boxes
377(`hint.threshold` trades one for the other). Boxes under 4×4 logical pixels
378are dropped.
379
380NeferWL starts `nefer-hints` at the first hint scan (loading takes about half a
381second), keeps it running, and stops it on exit. If it dies, fails or takes
382more than 2 seconds on a scan, that scan is cancelled and a new process starts
383at the next one. Its device (GPU or CPU) is logged at startup, at info level.
384
385### Requirements
386
387- The `nefer-hints` binary, found in `PATH` or named by `hint.detector`.
388- Its model files, in `hint.model`.
389- A Vulkan GPU for speed; without one the detector falls back to the CPU, which is slower.
390
391### Debugging hint mode
392
393With `hint.enable = on` and `NEFERWL_HINT_DEBUG=1` set when NeferWL starts (for example `NEFERWL_HINT_DEBUG=1 make tty`, or the variable in the launch environment), every successful scan writes three files to `$XDG_STATE_HOME/neferwl/hints/` (`~/.local/state/neferwl/hints/` when unset): `<time>-<output>.png`, the frame as scanned; `<time>-<output>.annotated.png`, the same with the detector boxes outlined; and `<time>-<output>.json`, the targets (rectangle and score) and the capture, detection and total timings. NeferWL keeps the 50 most recent scans and logs a warning at startup. The detector's own messages are logged at debug level (`log.debug = hints`). The files contain the screen in clear: delete them after use.