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Use Imagemagick to merge multiple favicon.ico files into one

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Given a number of favicon.ico files at multiple resolutions, merge them into one favicon.ico file using Imagemagick and the convert utility:

apt-get or brew works here, depending on your flavor:

# apt-get install Imagemagick
...
# exit
$ which convert
/usr/bin/convert
$ man convert
NAME
  convert - convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more.
SYNOPSIS
  convert [input-options] input-file [output-options] output-file
...
$
$ convert favicon_16.ico favicon_32.ico favicon_57.ico favicon_72.ico favicon_114.ico favicon.ico
$