Disclaimer Copyrights for below content belongs to MFH. Videos are uploded to MFH Youtube channel and made them unlisted or not accessable to public. We use youtube to have better controls on the video.

Lesson Notes

whoami – get know which user you are in

su root – by using this command we can switch user from one user to other but we should know crendintials.so we will not be able switch another user

Sudo is superuser do as it will be switching user without credentials  

we will use this – Sudo su root 

Cal and date are commands, by using this we can see calendar and date 

they are3 types of users 

1)owner 

2)group 

3)others 

we will be giving the permissions to these 3 users by using chmod command 

to give permission we will follow the numeric and aliphatic order 

3 types of permissions are Available  

they are 

r – read w – write x – execute 

so, we have total 9 columns for single file like this 

owner   group   others 

—     —     — 

rwx     rwx     rwx 

we follow the numeric number  

r = 4 w = 2 x = 1 

we need to calculate this number for giving permissions to 3 types of users 

we using  chmod  777 f1 then it will give read, write and execute permissions to owner, group and others 

exp: chmod  777 

                Owner    group     others              

                 rwx         rwx          rwx 

                4+2+1     4+2+1      4+2+1 

                    7              7              7    

alphabetical notations 

———————– 

It is another type of method to change permissions. here we can take 1 letter from the 3 users 

users  

owner———-u 

group———-g 

others———o 

we can denote the 

            “u” denotes the owner user 

              “g” denotes the group user 

              “o” denotes the others user 

so, we need to use these letters to change permissions of files. 

two symbols also we will use in changing permissions 

 Addition and subtraction 

“+” addition symbol is used to add permission to file. 

“-” subtraction symbol is used to removing the permissions to file. 

+ = adding permissions 

– = removing the permissions 

here we can change the permission by using alphabetic order. 

Here we will  

          1)removing the OWNER{X} executing permission from user 

          2) no change in group permissions 

           3)adding READ{R} PERMISIONS from others user 

then we will get this format 

example: – 

rwx rw     ec2-user ec2-user file1  >>>>>>>>>   rw  rw   r 

— — —                                      — — — 

After changing the alphabetic permissions 

rwx rw  r   ec2-user ec2-user file1  >>>>>>>>>   rw  rw  r    === chmod u-x,o+r   

— — —                                                                        — — —   

chmod=x  for replacing the older permissions