Re: [dev] [query] A tool for filtering lists of filenames with return codes

From: Evan Gates <>
Date: Fri, 20 May 2016 07:29:28 -0700

On Thu, May 19, 2016 at 5:09 PM, Eric Pruitt <> wrote:
> I wrote a tool for filtering lists of files based on return codes of
> subprocesses called "query:" .
> Find all dynamically linked executables:
> find -type f | query sh -c 'ldd "$QUERY_FILENAME"'
> Find all files ending in ".json" that are malformed:
> find -type f -iname '*.json' | query -s ! python -m json.tool
> The tool should pretty portable. I haven't tested it on FreeBSD or
> OpenBSD yet, but I was able to compile it on Mac OS X. I am using
> signal(2) whose behavior varies across platforms, but I don't think that
> will be a problem in practice since the handler only calls exit(3).
> Please let me know what you think of the idea and code.
> Thanks,
> Eric

This ability is already built in to find using the -exec primary. And
newline delimited lists of files are not safe. If the program you are
piping to supports nul delimited lists you can print them in POSIX
find by doing

    find . -exec printf '%s\0' {} +

and in many other finds (e.g. GNU) by doing

    find . -print0

For your first example

    find . -type f -exec sh -c 'ldd "$1" >/dev/null 2>&1' sh {} \; -print

or better, yet, fewer instances of sh

    find . -type f -exec sh -c 'for f do ldd "$f" >/dev/null 2>&1 &&
printf %s\\n "$f"; done;:' sh {} +

These examples do just print the filenames, so they are for visual
inspection only. If you want to do something with those filenames, do
so in exec, or print them with nul delimiters (but really... just

That being said, cool tool!

Received on Fri May 20 2016 - 16:29:28 CEST

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