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I'm looking for an image viewer that takes data on stdin and can be run like:

cat image.png | imageviewer
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ImageMagick's display program will do just that, assuming you pipe it something that it understands.

cat image.png | display

and it'll pop up a window showing that image.

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On version ImageMagick 6.8.8-1 Q16 i686 2014-01-04 I need to also pass - as a parameter: $ cat image.png | display - or $ display - < image.png. – Emil Lundberg Jan 27 '14 at 19:52

ImageMagick's display.

display < foo.png
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On Linux (and likely BSDs), almost all of them – if you give /dev/stdin as the path. This includes: xloadimage, feh, Eye of GNOME (eog).

eog /dev/stdin < "$file"

(Not all of them work well with special files, though. GThumb failed the test, for example.)

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This doesn't work: cat graph.png | eog /dev/stdin – bukzor Apr 13 '11 at 16:03
@Naga: The < "$file" was an example. The point was whether the program can accept an arbitrary stream, be it a simple redirection or something more advanced (such as providing an image via stdin, a named pipe, process substitution, a socket, or a character device). The problem is that many viewers require the fd to be seekable, which only regular files and block devices are. – grawity Jun 20 '11 at 18:56
As @bukzor pointed out, cat graph.png | eog /dev/stdin fails, but eog /dev/stdin < graph.png works. – Denilson Sá Jan 3 '12 at 17:18
Is there any way to make this method work with piping (|) as well? – Tarrasch May 12 '12 at 16:05
It looks like eog is looking up information on the file descriptor (which succeeds in the special case that it was redirected directly from a file), whereas normal Unix programs will just take the input regardless of where it comes from. So eog won't work for general stdin. Another program that works is gwenview /dev/stdin (the KDE image viewer). – Mechanical snail Mar 4 '14 at 4:13

A FIFO could work with eog's lack of piping support:

mkfifo ${tmpfilename};
cat ${file} > ${tmpfilename} &;
eog /dev/stdin < ${tmpfilename};
rm ${tmpfilename};

AFAIK this should work.

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