chmod permissions

Ordinary wr uses
chmod 666 folder

example:

$ chmod u+x file to increase the execution permission
to the owner of the file $ chmod 751 file to assign the permissions of read, write and execute (7) to the owner of the file, and to the group where the file is located Assign permissions to read and execute (5), and assign permissions to execute (1) to other users
$ chmod u=rwx,g=rx,o=x file Another form of the above example
$ chmod =r file Assign to all users Read permission
$ chmod 444 file Same as above
$ chmod a-wx,a+r file Same as above
$ chmod -R u+r directory Recursively assign read permission to the owner of all files and subdirectories in directory
$ chmod 4755 Set with ID, assign read, write, and execute permissions to the owner, and assign read and execute permissions to groups and other users.