Basics of the Linux File System
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by quatre407


Welcome to the wonderfull world of Linux! :-) This text will hopefully give you a nice quick crash course in what the linux file system is. Obviously it isn't very detailed (or long) but it should help aid you in your attempts to learn/hack/crack a Linux based system. 

Basic knowledge:
linux uses ext2 file system mainly, but some have switched to reiserFS
linux is case sensitive so LS is't Ls isn't ls.
linux has many diffrent distrobutions so not all this info could be
aplicable to your system.
linux is good.

INFORMATION DUMP:
/ is the root directory (not to be confused with roots home directory)
/home is where users home directories are (minus root)
/root is roots home directory
/var is where various logs are kept and temporary files
/usr various programs and definitions are kept here
/bin is where binaries are stored (ie: programs)
/opt is where optional and programs installed later *SHOULD* be put
/lib has various libraries
/etc houses all kinds of interesting configuration files and passwd
/boot in most cases stores boot config files, sometimes the kernel too
/mnt is where other disks *SHOULD* be mounted

Files that begin with a . are considered hidden files, but can be viewed by using the ls -la command and arguments. ls -la will aslo tell you the permissions on the file. Yous should see something like this

-rwx--x--x root root ...... which would mean that the file is owned by root, is owned by the root user group, and is read write and executible to the owner, but only exicutable to other group members and everyone else.

Home directories (/home/username) are protected from others entering or viewing the contents. root' home directory (/root) is also protected. To find out the permissions (ie: how they are protected) you can use ls -la in the /home/ directory. I've noticed a few universities changing the permissions on the home directories so that they are world readable ... thats a no no.

The system startup is in /etc/rc.d (NOTE: this may not be true for sysv based systems). In the bsd startup used by Slackware you have scripts that dictate what starts at boot time. To remove a service you can chmod a-x namofservice (if your the admin ;-)). chmod is the name of the command that changes permissions.

Well there it is, a very quickly slopped together idea of the linux file system. It's very elementry but you can find out more at these links:

http://www.linuxdoc.org
http://www.linuxiso.org
http://www.linuxnewbie.org
http://www.linux.com

... just to say a few. Go and get some knowledge :-)

<quatre407>