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I'm building my first Linux from scratch... now I've reached a point to mount some filesystems that I don't know what they are and what they're meant to do...! these are the commands that I'm gonna use:

mount -vt devpts devpts $LFS/dev/pts
mount -vt proc proc $LFS/proc
mount -vt sysfs sysfs $LFS/sys
mount -vt tmpfs shm $LFS/dev/shm

could somebody explain them to me, please?

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1 Answer 1

up vote 2 down vote accepted

These are all virtual filesystems, in the sense they don't exist anywhere in a physical disk, and are only file-based representations of data stored in the RAM (remember that everything is a file on UNIX-like systems).

  • /dev/pts: contains pseudo terminal devices (that's why Konsole, GNOME Terminal, etc. are terminal emulators)
  • /proc and /sys: exposes kernel's data structures to the userspace (/proc: mainly process-related stuff; /sys: devices, drivers and kernel settings)
  • /dev/shm: provides file-based shared memory (basically a RAM disk)
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where are these files before being mounted? I mean for example when we wanna mount a usb flash drive on a directory we point to a file (for example sdb2) in /dev representing the flash drive but in the mentioned mount commands we are pointing at nowhere (directly to a file that does not exist) ! –  morTie Jan 8 '13 at 0:54
1  
@morTie That's right. On these cases, it's not the files that matter, but the filesystems. I think you can use none as the filename, if it makes things clearer for you. –  Aluísio A. S. G. Jan 8 '13 at 1:00
    
Oops..! my mistake sorry... you are totally right :D –  morTie Jan 8 '13 at 1:20

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