Question { 64683 }

How many Layers in Network Layer ?

Answer

Network Layer are 7
1.Physical Layer
2.Data Link Layer
3.Network Layer
4.Transport Layer
5.Session Layer
6.Presentation Layer
7.Application Layer

Question { 12143 }

How to recover a deleted file in linux ?

Answer

single user mode
#init 1
#grep -b 'search-text' /dev/partition > file.txt
To recover text file starting with "nixCraft" word on
/dev/sda1 you can try following command:
# grep -i -a -B10 -A100 'nixCraft' /dev/sda1 > file.txt

Next use vi to see file.txt. This method is ONLY useful if
deleted file is text file. If you are using ext2 file
system, try out recover command. .

Question { 10789 }

linux file defaults permition

Answer

umask value = 022
Without a umask in effect,any file created will have 666
permissions.

666
022
---------
644
---------
A umask of 022 will result in files created with 666 permission.