Basic #1 Linux File System
To interact with the Linux file system, you must understand some basics: its key directories, some of the most commonly used commands, and the permissions you can assign to files.
Key directories in the file system:
*/: Root directory (base of file system)
/bin: Executable programs
/boot: Linux kernel and boot loader
/dev: Special device files
/etc: System configuration files
/home: Home directories of all users
/lib: Library files for programs
/media: Mount points for CD-ROM and and other media
/root: Home directory of the root user
*/sbin: System administration commands
/srv: Data for services such as Web and FTP
*/tmp: Temporary directory
/usr: Many of the important administration programs
/var: Various system files, such as logs
Basic #2 Linux Common Commands
Below is the list of Linux Common Commands that we used:
Basic #3 File Permission
Linux has inherited from UNIX the concept of ownerships and permissions for files. This is basically because it was conceived as a networked system where different people would be using a variety of programs, files, etc. Obviously, there's a need to keep things organized and secure. We don't want an ordinary user using a program that could potentially trash the whole system. There are security and privacy issues here as well. Below is some example on File Permission attributes on Linux:
rwxrwxrwx: Three sets of rwx. The leftmost set pertains to the owner, the middle set is for the group, and the rightmost set is for others; rwx stands for read (r), write (w), execute (x); the dash (-) means no permission.
rwx------: Only the owner can read, write, and execute.
rw-r--r--: Everyone can read, and the owner can also write.
rw-------: Only the owner can read and write.
r--r--r--: Everyone can read.
Permissions can also be expressed numerically, where read (r) is equal to 4, write (w) is equal to 2, execute (x) is equal to 1, and no permission is equal to 0. Therefore, rwxrwxrwx is equal to 777, rwx------ is equal to 700, rw-r--r-- is equal to 744, rw------- is equal to 600, and r--r--r-- is equal to 444.