Re: Enhancement Request for sha256sum - output only the SHA-256 hash alone

[Bob Proulx]

Pádraig Brady wrote:
> jens wrote:
> > It would make shell scripts that use sha256sum much simpler. Currently it
> > is necessary to split the output of sha256sum to obtain the hash, which
> > usually requires an additional command / Unix process.
> 
> This is one of those trade-offs.
> I'd be 60:40 against adding such an option,
> because it's so easy to implement with cut(1):

I feel that way too.  It's just so easy to do in the shell.

>   sum=$(sha256sum file | cut -d ' ' -f 1)
> 
> Yes that's an extra process, but you can easily
> enough avoid that on any POSIX shell using:
> 
>   sum=$(sha256sum file) && sum=${sum%% *}

I'll suggest always using stdin instead ("sha256sum < file") as that
avoids any possible quoting of things to get in the way.  In the case
where the filename contains special characters.

And then just to show yet a different way to keep from using external
processes.

    set -- $(sha256sum < file) && sum=$1

But this does assume one is no longer using the positional arguments
at that point.

Bob