Software & Apps Linux sha1sum - Linux Command - Unix Command The 'sha1sum' command both creates and verifies SHA1 checksums Share Pin Email Print Linux Switching from Windows By Juergen Haas Writer Former Lifewire writer Juergen Haas is a software developer, data scientist, and a fan of the Linux operating system. our editorial process Juergen Haas Updated February 05, 2020 Use the sha1sum utility in Linux to print or check SHA1 (160-bit) checksums. Synopsis The command takes the following general forms: sha1sum [OPTION] [FILE]...sha1sum [OPTION] --check [FILE] Options Modify the command's output using the following flags: -b, --binary: Read files in binary mode (default on DOS/Windows).-c, --check: Check SHA1 sums against given list.-t, --text: Read files in text mode (default).--status: Don't output anything, status code shows success.-w, --warn: Warn about improperly formated checksum lines.--help: Display this help and exit.--version: Output version information and exit. How the Program Works The sums are computed as described in FIPS-180-1. To create an SHA1 checksum for a file, run sha1sum filename > filename.sha1. This process writes to the output of sha1sum to a file ending with an .sha1 extenstion. To verify that the file's checksum matches, use the -c flag upon that outputted checksum. For example, sha1sum -c filename.sha1. If the file verifies correctly, you'll receive an OK response. The file you're checking, as well as the checksum file, must be in the same directory.