check is a simple commandline utility to calculate CRC-32 or Adler-32 checksums on the fly (that is, as a filter within a command pipeline), or to calculate such checksums on a list of files given as arguments. It is fast and was designed to be used for verification of backups and archives written to semi-reliable media (e.g., tapes), but it can also be used to compare files against versions stored within ZIP archives (same CRC) or to verify one-to-many copies without the need for multiple byte-for-byte comparisons.
