When I install imageMagick,it told me must link
libpng before install imageMagick.
Then I link the
libpng,it occur this issue
brew link libpng Linking /usr/local/Cellar/libpng/1.6.17... Error: Could not symlink include/libpng16/png.h Target /usr/local/include/libpng16/png.h already exists. You may want to remove it: rm '/usr/local/include/libpng16/png.h'
To force the link and overwrite all conflicting files:
brew link --overwrite libpng
To list all files that would be deleted:
brew link --overwrite --dry-run libpng