Скачать или смотреть Listing files and directories in Linux

Topics covered in this video:
What is inode?
Advantages of inode?
Types of Files(Symbol Type of File)
How to create Symbolic Link
How to create Hard link
What is Grep(Global Regular Expression Print)
Filter Commands
Listing files and directories
linux basic commands

Listing files and directories:
#ls (list the file names)
#ls -a (Displays hidden files and directories)
#ls -l filename (to see the permissions of a particular file)
#ls -l (long listing of the file)
#ls –l (filename to see the permissions of a particular file)
#ls -al (shows the files in ascending order of modification.)
#ls p* (All the files start with p.)
#ls -d /* or ls -ld /*( Directory listing only )
#ls –ld directory name (to see the permissions of a particular directory)
#ls [!ae]*(! Symbol complements the condition that follows. The characters must not be a or e.)
#ls -i or ls -li (displas inode numbers of file and directories)

What is inode?
Inodes keep track of all the files on a Linux system. Except for the file name and the actual content of the file, inodes save everything else. It's like a file-based data structure that holds metadata about all of the files in the system.

Types of Files(Symbol Type of File):
- Normal file
d - Directory
l - Link file (shortcut)
b - Block file (Harddisk, Floppy disk)
c - Character file (Keyboard, Mouse)

Soft Link Hard link
-------------------------------------- --------------------------------------
1.Size of link file is equal to no. of 1.Size of both file is same
characters in the name of original file

2.if original file is deleted, link is broken 2.If original file is deleted then also
and data is lost. link will contain data.

3.SHORTCUT FILE 3.BACKUP FILE

Grep(Global Regular Expression Print):
Grep stands for Global Regular Expression Print. It is used to pick out the required expression
from the file and print the output. If grep is combined with another command it can be used to
pick out the selected word, phrase from the output of first command and print it.

Example o Grep:
Let us pick the information about root from the file /etc/passwd (/etc/passwd contains
information about all the users present in the system)

1. To find Kernel word in the file
#grep root /etc/passwd (

2. To avoid case sensitivity of the word (i.e. the word may be uppercase of lowercase) use -i
(lets grep the word kernel whether upper of lower case in the file ktfile)
#grep –i root /etc/passwd

3.To display the things except the given word:
#grep –v kernel ktfile

4. To display the searched word in color
#grep --color root /etc/passwd

5. To display a word and 2 lines after the word:
#grep –nA2 wheel /etc/group

6. To display a word and 2 lines above the word:
#grep -nB2 wheel /etc/group

Filter Commands:
Filter commands are used to filter the output so that the required things can easily be
picked up. The commands which are used to filter the output
1. less:
The less command is used to see the output line wise or page wise.
2. more:
more is exactly same like less
:q (to quit from the file)
Use d to go to next page
Use / to search for a word in the file
Use v to go vi mode where you can edit the file and once you save it you will back to
more command
Note: press Enter key to scroll down line by line (or)
3.head
It is used to display the top 10 lines of the file.
Ex:# head /etc/passwd
4.To display the custom lines
#head -n /etc/passwd (where n can be any number)
eg: head -2 /etc/passwd ( second line will display from top of the file)
4.tail
It is used to display the last 10 lines of the file
To display the custom lines
5.sort
It is used to sort the output in numeric or alphabetic order
To sort the file according to numbers
To remove the duplicate entries from the output
6.cut command:
The cut command is used to pick the given expression (in columns) and display the output.
7.sed command:
sed stands for stream editor, which is used to search a word in the file and replace it with the
word required to be in the output

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#inode
#SymbolicLink
#HardLink
#GrepCommand
#Filter Commands
#ListingFilesAndDirectories