On a Linux system, file hashes can be generated using the md5sum, sha256sum, and sha1sum utilities:
$ md5sum log.exe
6e4e030fbd2ee786e1b6b758d5897316 log.exe
$ sha256sum log.exe
01636faaae739655bf88b39d21834b7dac923386d2b52efb4142cb278061f97f log.exe
$ sha1sum log.exe
625644bacf83a889038e4a283d29204edc0e9b65 log.exe
For Windows, various tools for generating file hashes can be found online. HashMyFiles (http://www.nirsoft.net/utils/hash_my_files.html) is one such tool that generates hash values for single or multiple files, and it also highlights identical hashes with same colors. In the following screenshot, it can be seen that log.exe and bunny.exe are the same samples based on their hash values:
You can get a list and comparison of various hashing tools here: https://en.wikipedia.org/wiki/Comparison_of_file_verification_software. Feel free to choose the ones that best suit your needs after a careful review.