Using rename on the command line

Examples

for everything that includes the phrase epicgames-2019:

rename 's/epicgames-2019/beijing-2020/' *epicgames-2019*

for every file in the current directory:

replace the first instance of a lowercase letter with an uppercase version of itself

rename 's/([a-z])/\U$1/' ./*

Changing case with transliteration of characters using y/

rename 'y/A-Z/a-z/' ./*

source: https://stackoverflow.com/a/45641840
description of y/: https://www.gnu.org/software/sed/manual/sed.html#Other-Commands