Calculate an actual file
Run GNU md5sum against the file you want to check. Quote paths with spaces. The double dash ends options, so a filename beginning with a hyphen is not treated as another flag. This command hashes bytes from the file, not the displayed filename.
md5sum -- 'example.zip'
The output contains a digest and a filename marker. When using the browser's expected-value field, copy only the 32 hexadecimal characters. The manifest syntax used by md5sum is a different input format and is not accepted as a single expected digest.
Check a checksum manifest
Obtain a manifest from a trusted publisher and inspect its listed filenames. Run from the directory relative to which those paths were written. Avoid treating a downloaded manifest as proof of publisher identity.
md5sum --check checksums.md5
Read all diagnostics and the command's exit status. An unreadable or missing file is different from a file whose calculated hash does not match. A successful check only establishes agreement with the listed values; it does not scan for malware or authenticate the manifest.
Reproduce the abc fixture without a newline
printf emits the bytes requested here without the line ending commonly added by echo. A shell's echo behavior and options can vary, so printf is a clearer controlled test.
printf '%s' 'abc' | md5sum
The digest should be 900150983cd24fb0d6963f7d28e17f72. The hash of abc followed by a newline is a different value. The browser's text tool preserves input and lets you reproduce this difference; the file tool should be used for the exact bytes of a saved artifact.
Batch and filenames are not the same task
Hashing one complete text file is not the same as hashing each text line independently. The browser's line mode removes record separators from each record, preserves source line numbers and can include empty records explicitly. A checksum manifest, by contrast, associates already calculated values with paths.
For names containing unusual characters, preserve the manifest format produced by the utility rather than manually reconstructing it. Do not open a CSV export as an md5sum manifest; CSV has its own quoting rules.
Choose the algorithm requested by the publisher
Use sha256sum for a SHA-256 manifest; changing the command changes the function, not just the display length. MD5 is useful for required legacy checks and accidental-change diagnostics, but is unsuitable where collision resistance is a security requirement. Keep both the reference source and the file version in your verification notes.