从 Linux 命令行仅生成 SHA-256 hash

Question

I'm looking for a single command that emits just the sha256 hash, as a hexadecimal number, of the contents of a single supplied file.

I am aware of shasum -a 256 , openssl dgst -sha256 , sha256sum et al. but they all emit other information together with the checksum and I would like to avoid the need for post-processing the result with sed or some such.

Answer 1

You may use:

sh -c 'shasum < "$1" | cut -d" " -f1' -- "$file"

Answer 2

The following perl one-liner actually seems to satisfy all my stated requirements:

perl -e 'use Digest::SHA;' -e 'use warnings;' -e 'use strict;' -e 'use autodie;' -e 'my $sha = Digest::SHA->new(256); open my $fh, $ARGV[0]; $sha->addfile($fh, "b"); print $sha->hexdigest . "\n";' "$file"

In particular it is safe for "funny" file names and can be used for arbitrary shell scripting, including as a find --exec argument (which is one thing I need it for).

(I have not written in Perl for a very long time, so the above can probably be improved.)