Many times you might want to fine tune the default permissions of the files created on a linux system. This is very simple and usually if you are using bash all you have to do is to define somewhere in the bash startup files (/etc/profile is a good place for this) a new value for umask like this:
(this will allow by default group write permissions on the newly created files)
Normally on modern linux distributions this is by default set to 022 and you can easily find out what it is on your system by running the umask command:
Contrary to what you might think, this is not enough to have this working for all applications and daemons on the system. This works fine for any files created from a shell session, but the files created by other processes, like the web server for example, will still use the default, unless otherwise configured. In order to have apache use a different umask we can define this inside /etc/apache2/envvars (debian, and ubuntu systems) or /etc/sysconfig/httpd (rhel,centos systems) like this:
and restart apache to enable it.
Other daemons will have different locations where you can define this to overwrite the default setting for umask (check their documentation if you are unsure).