There are a lot more ways to check files using if commands than many of us realize. Although this information is included in the bash man page, that man page has thousands of lines and you could easily find yourself paging down more than 100 times to reach it.
This post, provides information on each option and examples for some of the most useful ones.
[ Get regularly scheduled insights by signing up for Network World newsletters. ]
Checking if a file exists
One of the most commonly used tests for checking on files is if [ -f filename ]. This test will result in true if the file exists and is a regular file—not a directory or a symbolic link. You might use it like this:
Source:: Network World – Linux