What are /proc, /dev and /sys?

audiodef · Posted: Tue Mar 20, 2018 6:09 pm Post subject: What are /proc, /dev and /sys?

I've been doing a bunch of Gentoo installs recently, and I realized I don't really know what the /proc, /sys and /dev mounts are when chrooting. What exactly are they and why are they needed?
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NeddySeagoon · Posted: Tue Mar 20, 2018 6:35 pm Post subject:

audiodef,

/proc and /sys both expose internal kernel data structures as files.
Some things are read/write, some read only and a some write only.
You can read and change kernel behavior here.

With a kernel using DEVTMPFS /dev contains all the device special nodes for the hardware that the kernel can see.
eg /dev/sda is the entire first HDD detected by the kernel.

Without /dev mounted, grub could not be installed ts the MBR.
/dev/pts in needed for pseudo ttys.

Not mounting /proc and /sys breaks other things.
Try it, its harmless.
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fedeliallalinea · Posted: Tue Mar 20, 2018 6:37 pm Post subject:

https://unix.stackexchange.com/questions/188886/what-is-in-dev-proc-and-sys
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audiodef · Posted: Tue Mar 20, 2018 7:00 pm Post subject:

Very cool, thank you both.
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