How to find out if a file exist or does not exist in bash shell

With the help of BASH shell and IF command, it is possible to find out if a file exists or not on the filesystem. A conditional [removed]also know as ‘evaluating expressions’ can be used by [[ compound command and the test ([) builtin commands to test file attributes and perform string and arithmetic comparisons. This tutorial explains how to tell if a regular file exist in Bash under Linux or Unix-like system.