chmod usage
The three rightmost digits define permissions for the:
file user, the group, and others.
Example usage: sudo chmod 777 testfile.txt
# Permission rwx Binary
7 read, write and execute rwx 111
6 read and write rw- 110
5 read and execute r-x 101
4 read only r-- 100
3 write and execute -wx 011
2 write only -w- 010
1 execute only --x 001
0 none --- 000