Example#$1$: Chmod u$=$rw file$1$

Change the permissions for the owner of example.jpg so that the owner may read and write the file. Do not change the permissions for the group, or for others.

Example#$2$: chmod $u+s$ comphope.txt Set the "Set$-$User$-$ID$"$ bit of comphope.txt$,$ so that anyone who attempts to access that file does so as if they are the owner of the file.

Question: Find Set permission for the following commands:

chmod u$-$s comphope.txt

chmod $a=$ rw file.txt

Q$3$: explain the following permission:

$ chmod $u+r,g+x$ filename

$ chmod u$-$rx filename

$-rW-r-r-$

$-$rwxrwxrwx

$ chmod $667$ filename

$ chmod $251$ filename