#415 Inconsistent Behavior w/ input_file Parameter

[Dan Rossiter]

I just came across some inconsistent behavior that seems like it may be a bug. It's either that or a deficiency in documentation. See the following examples of what works and what does not.

This does not work (colon and no file extension):
/usr/bin/gm convert :/tmp/this_is_a_png -resize 200x200 -background white -flatten png:-

This works (colon and file extension):
/usr/bin/gm convert :/tmp/this_is_a_png.png -resize 200x200 -background white -flatten png:-

This works (no colon):
/usr/bin/gm convert /tmp/this_is_a_png -resize 200x200 -background white -flatten png:-

I believe that this worked in ImageMagick before I made the switch to GM. This is not necessarily relevant to whether this is a bug or not, but a datapoint.

All of this, however, is without looking at docs for convert covering the input_file + colon notation. If such documentation exists that would be useful.

-Dan

[Bob Friesenhahn]

Thanks for reporting this. Mercurial changeset 15012:33569d74cf0c now eliminates any special handling (does not save an empty magick or remove colon from filename) for filenames which start with a colon.

The documentation is pretty clear regarding format prefixes (look for section entitled "FILES AND FORMATS"), but an empty format specifier should obviously be ignored since it can't provide any useful information and it distorts any resulting error information.