ls command is your friend.. :)

How to know the inode of a file of directory:
$ls -i <- displays the innode of the file& directory in current directory
Ex:
$ ls -i
320785 a 320800 abc 320786 b 320787 c
The numbers represents the inode

How to list files sorted with modification time:
$ls -lt <- displays with time sorted manner with latest first
Ex:
$ ls -lt
total 4
-rw-r--r-- 1 hanu hanu 0 Aug 26 11:54 c.odt
drwxr-xr-x 2 hanu hanu 4096 Aug 26 11:53 empty_dir
-rw-r--r-- 1 hanu hanu 0 Aug 26 11:53 a.txt
-rw-r--r-- 1 hanu hanu 0 Aug 26 11:53 b.png

Note: if you want to reverse the output of ls add option -r
Ex:
$ ls -ltr
total 4
-rw-r--r-- 1 hanu hanu 0 Aug 26 11:53 b.png
-rw-r--r-- 1 hanu hanu 0 Aug 26 11:53 a.txt
drwxr-xr-x 2 hanu hanu 4096 Aug 26 11:53 empty_dir
-rw-r--r-- 1 hanu hanu 0 Aug 26 11:54 c.odt

Using "ls" and "find" command how to display only directories..?

Following commands list only directories in the current directory.

1. #ls -l | grep ^d

2. #ls -d */

3. #find -type d
Ex: #find /tmp -type d <-- This command shows all the directories with in the /tmp directory.

Want only files to be listed.. use 1. #ls -l | grep -v ^d

2. #find -type f
Ex: #find /tmp -type f <-- This command shows all regular files with in the /tmp directory.