How to change permissions to certain file pattern/extension?

use find:

find . -name "*.sh" -exec chmod +x {} \;

Try using the glorious combination of find with xargs.

find . -iname \*.sh -print0 | xargs -r0 chmod +x

The . is the directory to start in, in this case the working directory.

With modern versions of find, you get the benefits of an xargs approach that avoids multiple calls to the command (chmod). The command is only slightly different.

find . -name "*.sh" -exec chmod +x {} +

Snip from find docs on Arch 2015.09.01 (emphasis added by me):

-exec command {} +

This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of {} is allowed within the command. The command is executed in the starting directory.