Question

Create by using Linux server

• Create a file name it foo.txt
• Remove all permissions from foo.txt
• What happen if you try to read the file?
• Change foo.txt permission to read and write only for owner
• Change foo.txt permission to read for group
• Change foo.txt permission to read and write everyone

Answer 1

1) Create a file name it foo.txt

Solution :

vi foo.txt

press i for input mode in linux and write the content and then save it with :wq!

ls -l (to see the permission of files in the current directory)

total 8
-rw-r--r-- 1 runner runner 13 Oct 14 04:46 foo.txt
-rw-r--r-- 1 runner runner 31 Oct 14 04:46 main.sh

2) Remove all permissions from foo.txt

It can be done with chmod option and remove all permissions of owner group and others with 000 respectively.

chmod 000 foo.txt

ls -l

total 8
---------- 1 runner runner 13 Oct 14 04:46 foo.txt
-rw-r--r-- 1 runner runner 31 Oct 14 04:46 main.sh

3)  What happen if you try to read the file?

It will be showing permissioned denied because its permission to read has been revoked.

cat foo.txt
cat: foo.txt: Permission denied

4)  Change foo.txt permission to read and write only for owner

chmod 600 foo.txt
ls -l
total 8
-rw------- 1 runner runner 13 Oct 14 04:46 foo.txt
-rw-r--r-- 1 runner runner 31 Oct 14 04:46 main.sh

5)  Change foo.txt permission to read for group

chmod 640 foo.txt
ls -l
total 8
-rw-r----- 1 runner runner 13 Oct 14 04:46 foo.txt
-rw-r--r-- 1 runner runner 31 Oct 14 04:46 main.sh

6)  Change foo.txt permission to read and write everyone

chmod 646 foo.txt

ls -l
total 8
-rw-r--rw- 1 runner runner 13 Oct 14 04:46 foo.txt
-rw-r--r-- 1 runner runner 31 Oct 14 04:46 main.sh