Search notes:

Shell command: chmod

chmod changes the file mode bits.
A file's file mode bits determine who is able to read, write or execute a file.

Making a file read only

Removing the w flag makes a file read only.
The following command removes the w flag for everyone (a = all) 
chmod a-w readme.txt
The following command adds the w flag for the file's owner (u = user) so that at least the owner of the file can change it: 
chmod u+w readme.txt
The following command removes the r flag from others (o) so that the «rest of the world» cannot read the file: 
chmod o+w readme.txt

Changing files to 644, directories to 755

Uppercase X (+X) set the executable bit for directories only. 
chmod -R a=r,u+w,a+X /path/to/directory

See also

umask
chattr to change file attributes.
Shell commands

Index

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