问题:

I've upgraded my Homebrew ImageMagick to 6.9.4-7 version (Mac OS 10.11.5), after which it doesn't understand brackets in file names anymore.

This command should consider the first frame of a picture:

identify -format '%wx%h,1' 'some_pic.jpg[0]'

For JPG it is actually just the picture, so the command is equivalent to:

identify -format '%wx%h,1' 'some_pic.jpg'

The bracket command works fine on my Ubuntu server and worked before on my Mac. But now it fails with

identify: unable to open image `some_pic.jpg[0]': 
No such file or directory @ error/blob.c/OpenBlob/2705.

Btw, this is the reason behind Paperclip::Errors::NotIdentifiedByImageMagickError on my local machine.

回答1:

Manually installing imagemagick-6.9.3-10 via brew has fixed the problem. So I believe it's a bug in imagemagick.

PS: To install specific version via brew, run

brew edit imagemagick

And edit these lines:

url "https://dl.bintray.com/homebrew/mirror/imagemagick-6.9.4-7.tar.xz"
mirror "https://www.imagemagick.org/download/ImageMagick-6.9.4-7.tar.xz"
sha256 "f54fc8dcdb328404d1f89ddebe75d603e22894d3786ca2f2a9677478135b4c86"

May not work if the version you choose (https://dl.bintray.com/homebrew/mirror/) is not compatible with the rest of the brew formula. Then you need to go deeper.