git shasum and node sha1 do not produce the same hashe

Question

$ echo -e 'blob 14\0Hello, World!' | shasum

produces: 8ab686eafeb1f44702738c8b0f24f2567c36da6d

running this in js/node:

var sha1 = require('sha1');

const fileContents = "Hello, World!";
const length = fileContents.length + 1;

const blobString = `blob ${length}\0${fileContents}`;

const hash = sha1(blobString);

console.log(blobString);
console.log(hash);

produces:

blob 14Hello, World!
d4fcfe4d339d4e59d168fdf3c0ad445fa980a7d6

why are the hashes not equal ? (8ab686eafeb1f44702738c8b0f24f2567c36da6d != d4fcfe4d339d4e59d168fdf3c0ad445fa980a7d6)

Answer 1

The hashes are not equal because of the difference of a newline character in the input. echo adds a newline. Use printf instead:

printf 'blob 14\0Hello, World!' | shasum
# prints: d4fcfe4d339d4e59d168fdf3c0ad445fa980a7d6

This works too, but not as portable, because the flags of echo are not supported predictably in all systems:

echo -ne 'blob 14\0Hello, World!' | shasum