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notcurses-demo(1) notcurses-demo(1)


notcurses-demo - Show off some notcurses features


notcurses-demo [-h|–help] [-p path] [-d delaymult] [-l loglevel] [-f renderfile] [-J jsonfile] [-m margins] [-ikVc] demospec


notcurses-demo demonstrates the capabilities of the notcurses library. It can be run in any terminal emulator or console with a correct terminfo(5) database, but is at is best in a 24bpp TrueColor RGB environment. If notcurses-demo seems to generate garbage, something is likely configured in a way that is going to prevent notcurses from working.

The demonstrations include (see NOTES below):

(a)llglyph—scroll the glyphs of your font
(b)oxes—pulsating boxes with a transparent center
(c)hunli—the strongest woman in the world
(d)ragon—the Harter-Heighway dragon curve
(e)agle—they took some time off my life, back in the day
(f)allin’—the screen falls apart under heavy blows
(g)rid—a gradient of color lain atop a great grid
(h)ighcon—high contrast text atop various colors
(i)ntro—a setting of tone
(j)ungle—low-bandwidth color cycling reveals ancient ruins
(k)eller—the miracle of sight, and painting with Braille
(l)uigi—a dashing Apennine plumber in a world of fire
(m)ojibake—a selection of market-price emoji
(n)ormal—a normal map of a friend, with effects
(o)utro—a message of hope from the library’s author
(q)rcode—quick response codes (from ISO/IEC 18004:2015)
(r)eel—demonstration of the ncreel high-level widget
(s)liders—a missing-piece puzzle made up of colorful blocks
(t)rans—an exploration of various transparencies
(u)niblocks—a series of blocks detailing Unicode pages
(v)iew—images and a video are rendered as text
(w)hiteout—a great Nothing slowly robs the world of color
(x)ray—stimulate a logo with energy
(y)ield—the best laid schemes o’ mice an’men gang aft agley
(z)oo—see the marvelous widgets of the notcurses world

At any time, press `q' to quit. The demo is best run in at least an 80x45 terminal.


-p path: Look in the specified path for data files.

-d delaymult: Apply a non-negative rational multiplier to the standard delay of 1s.

-l loglevel: Log everything (log level 8) or nothing (log level 0) to stderr.

-f renderfile: Render each frame to renderfile in addition to the screen.

-J jsonfile: Emit JSON summary of run to jsonfile.

-m margins: Define rendering margins (see below).

-k: Inhibit use of the alternate screen. Necessary if you want the output left on your terminal after the program exits.

-c: Do not attempt to seed the PRNG. This is useful when benchmarking.

-i: Continue after a failing demo.

-h: Print a usage message, and exit with success.

-V: Print the program name and version, and exit with success.

demospec: Select which demos to run, and what order to run them in. The default is ixezcydthnbkgmarwuvlsfjqo. See above for a list of demos.

Default margins are all 0, and thus the full screen will be rendered. Using -m, margins can be supplied. Provide a single number to set all four margins to the same value, or four comma-delimited values for the top, right, bottom, and left margins respectively. Negative margins are illegal.


Proper display requires:
A terminal advertising the rgb terminfo(5) capability, or that the environment variable COLORTERM is defined to 24bit (and that the terminal honors RGB escapes),
A monospaced font, and
Good Unicode support in your libc, font, and terminal emulator.

The Debian version of notcurses-demo leaves out certain multimedia considered non-free under the Debian Free Software Guidelines. As a result, the chunli, eagle, jungle, keller, luigi, and view demos are unavailable through the Debian package. This applies to any distro which uses the DFSG source tarball, including Ubuntu and Fedora.

If notcurses is built without multimedia support, the chunli, eagle, keller, outro, view, xray, and yield demos will be partially or wholly unavailable. If notcurses is built without libqrcodegen, the qrcode demo will be unavailable.

If notcurses-demo is run in a terminal lacking the can_change terminfo capability, the jungle demo will be skipped.

The following keypresses are recognized (and are also available from the menu):

Ctrl-U: Toggle the help screen.
H: Toggle the HUD. The HUD shows the most recent and current demos’ runtime and number of rendered frames. It can be grabbed and moved with the mouse.
Ctrl-R: Restart the demo.
q: Quit.

Benchmarking should be performed using -c to get a well-defined PRNG seed. JSON output via -J will probably be useful.


Certain demos (especially mojibake and allglyph) heavily exercise the font rendering stack. If your font or rendering engine draws glyphs with width different from that reported by the standard library’s wcwidth(3), Notcurses will have an incorrect notion of cursor placement, leading to undesirable behavior.


All code and design copyright Nick Black <>.
Images from Street Fighter II and Mega Man 2 copyright Capcom of America.
Images from Super Mario Bros. copyright Nintendo of America.
Images from Ninja Gaiden copyright Koei Tecmo America.
Images from Final Fantasy copyright Square Enix Co Ltd.
“Jungle with Rain” copyright Mark Ferrari/Living Worlds.


notcurses(3), ncurses(3NCURSES), wcwidth(3), terminfo(5)


nick black <>.