Week 3

Review questions:

        In any man page, there is a section titled "SEE ALSO". How is it
        useful ?      

        Define a hard link.

        Define a symlink.

        What is the difference between a hardlink and symlink.

        What character is used to separate component-file-names in a Unix
        pathname.

        List the names of subsections of man pages in section 3.

        What are disk partitions ? How will you learn about disks
        and disk partitioning methods ?

        What is the /tmp directory for ? What is its exclusive 
        permission that makes it critical for shared usage ?

        Define a filesystem. 

Unix directory structure:

        hier(7) man page in some Linux systems describes directory structure.
        filesystem(5) man page in Unix describes directory structure.

        Unix systems have huge number of files organized within directories.

        cd, pwd, mkdir, rmdir are some of the commands that are available
        for use with directories in the Unix system.

        On Unix systems that comprise of multiple disk partitions, different
        filesystems are anchored at different mount points. Thus a combination
        of filesystems maketh the Unix system directory structure.

        mount(1) commands list the various filesystems.

Unix file types:

        Regular file
        Directory
        Symbolic links to files
        Hard links to files
        Character device files
        Block device files
        Tmp/Pipe files (Unix version dependent)
        Socket files (Unix version dependent)

Unix vi command review:

        command mode [ also known as : mode ]
        Esc mode [ for searching, deleting etc ]
        Edit mode [ a, o, A, O, i, I ]

Unix commands for files/links/directories:

        cd, mkdir, rmdir, pwd, ln, rm, mv, cp, touch, ls, dirname, basename, 
        find, locate, chmod, chgrp, chown 

        File/directory archive commands - tar, cpio

Unix commands that operate on the contents of files: 

        cat, egrep, grep, pg, more, less, diff, bdiff 
	head, tail, awk, sed, uniq, sort
			- collectively known as filters. 

Files
-----
in unix everything is considered as a file.

device == file
	character device files aka character special files
		aka raw files
	block special files aka block device files
		aka block files
Regular files aka ordinary files 

process == file
memory == file
text files
binary files


directory

socket

link files
	hard link
	symbolic aka sym aka soft link

file is stream of data , stream of characters.

	identified by 
			name,
			size
			user owner
			group owner
			other owner
			inode number == index node number
			type + permissions = mode