Xephyr(1)

💖 Xephyr 💖

okay bestie, so this is the manual page for Xephyr — and it's part of the General Commands Manual crew, iykyk. it's an X server that outputs to a window on a pre-existing X display. let's get into it 🫶

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✨ NAME ✨

Xephyr — an X server that outputs to a window on a pre-existing X display. literally the whole vibe in one line 💅

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🌸 SYNOPSIS 🌸

Xephyr [:display] [option ...]

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🦋 DESCRIPTION 🦋

so Xephyr is a kdrive server that outputs to a window on a pre-existing "host" X display. think Xnest but with support for modern extensions like composite, damage and randr. no cap, that's the glow-up. ✨

unlike Xnest, which is an X proxy — meaning it's limited to the capabilities of the host X server — Xephyr is a real X server that uses the host X server window as a "framebuffer" via fast SHM XImages. it's giving main character energy fr fr. 👑

it also has support for "visually" debugging what the server is painting. so you can literally watch the paint happen. iconic.

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🎀 OPTIONS 🎀

the server accepts all the standard options of Xserver(1), plus these extra ones:

• -screen widthxheight — sets the screen size. you pick how big, bestie.
• -parent id — uses existing window id. and heads up: if a -screen argument follows a -parent argument, this screen is embedded into the given window. cute little nesting moment. 🪆
• -host-cursor — sets 'cursor acceleration': the host's cursor is reused. honestly this is only really there to aid debugging by avoiding server paints for the cursor. the performance improvement is negligible, so don't come for me expecting speed. 🙈
• -resizeable — allows the Xephyr window to be resized, even if it's not embedded into a parent window. by default, the Xephyr window has a fixed size. so if you want wiggle room, this is your girl. 💅
• -no-host-grab — disables grabbing the keyboard and mouse. that's it, that's the option.

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🔥 SIGNALS 🔥

send a SIGUSR1 to the server (like, e.g. pkill -USR1 Xephyr) to toggle the debugging mode. 🐛✨

in this mode, red rectangles are painted to screen areas getting painted, before painting the actual content. so you see the red boxes first, then the real stuff. very "behind the scenes" of it all.

the delay between this can be altered by setting a XEPHYR_PAUSE env var to a value in micro seconds. tune it to your heart's content. ⏱️

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💀 CAVEATS 💀

ngl, there's some stuff you should know:

• Rotated displays are currently updated via full blits. this is slower than a normal orientated display. debug mode will therefore not be of much use rotated. 😭
• the '-host-cursor' cursor is static in its appearance. no animation, just a still little guy.
• the build gets a warning about 'nanosleep'. "i think the various '-D' build flags are causing this. i haven't figured as yet how to work round it. it doesn't appear to break anything however." (that's the author talking, and honestly, relatable.) 🫠
• Keyboard handling is basic but works. lowkey fine.
• Mouse button 5 probably won't work. rip button 5. 🙏

none of these are dealbreakers, they're just the honest tea. ☕

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🌈 SEE ALSO 🌈

X(7), Xserver(1)

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👑 AUTHOR 👑

Matthew Allum <mallum@o-hand.com> — 2004. thank you for your service, legend. 🫡

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and that's the whole page, bestie!! this one's from X Version 11, shipping as xorg-server 21.1.25 — Xephyr(1), periodt. 💖✨🎀