cksum

Calculate checksum of file

$ cksum [file.txt]

$ cksum [file1] [file2]

$ echo "data" | cksum

$ cksum --algorithm sha256 [file.txt]

$ cksum -c [checksums.txt]

$ cksum --base64 [file.txt]

cksum [option]... [file]...

cksum computes a cyclic redundancy check (CRC) checksum and byte count for each specified file, or for standard input if no file is given. It is part of GNU coreutils and is commonly used to verify file integrity after transfers or copies.
By default, cksum uses the POSIX-standard 32-bit CRC algorithm. Modern versions of cksum (GNU coreutils 9.0+) support additional algorithms including MD5, SHA1, SHA256, and SHA512 via the --algorithm option, making it a versatile replacement for separate checksum utilities.
The output format includes the checksum value, byte count, and filename. When using the --check option, cksum can read previously generated checksum files and verify that the listed files have not been modified.

-a, --algorithm name

Select algorithm (crc, md5, sha1, sha256, sha512, etc.)

Read checksums and verify them

Digest length in bits

Output base64-encoded digest

Output raw binary digest

BSD-style checksum (default)

Reversed style without digest type

End lines with NUL instead of newline

Don't fail for missing files during check

Don't print OK for verified files

Silent mode, exit code shows result

Warn about malformed checksum lines

CRC32 is not cryptographically secure. Use SHA256 or stronger for security-critical verification. Reads stdin when no file given or file is -.

md5sum(1), sha256sum(1), sum(1)