Estou tentando instalar o GraphicsMagick no Mountain Lion e ter problemas. Eu tentei todas as coisas que eu poderia procurar em blogs e outras questões de stackoverflow, mas nada funcionou. Então eu coloquei a pilha completa de erros que recebo em cada comando. Por favor, olhe e me ajude.

Quando eu corro

brew install graphicsmagick

Eu entendi isso

Warning: Could not link jpeg. Unlinking...
Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
You can try again using `brew link jpeg'

e

Warning: Could not link libpng. Unlinking...
Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
You can try again using `brew link libpng'

e no último estou ficando

==> make install
Warning: Could not link graphicsmagick. Unlinking...
Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
You can try again using `brew link graphicsmagick'

Possible conflicting files are:
==> Summary
  /usr/local/Cellar/graphicsmagick/1.3.18: 283 files, 10M, built in 52 seconds

Agora, se eu tentarbrew link jpeg oubrew link libpng Eu recebo esse erro

Linking /usr/local/Cellar/jpeg/8d... Warning: Could not link jpeg. Unlinking...

Error: Could not symlink file: /usr/local/Cellar/jpeg/8d/bin/wrjpgcom
Target /usr/local/bin/wrjpgcom already exists. You may need to delete it.
To force the link and overwrite all other conflicting files, do:
  brew link --overwrite formula_name

To list all files that would be deleted:
  brew link --overwrite --dry-run formula_name

Se eu tentar o método de sobrescrever fazendobrew link --overwrite jpeg funcionou. Mas 'brew link --overwrite libpng' Eu entendi isso

Linking /usr/local/Cellar/libpng/1.5.14... Warning: Could not link libpng. Unlinking...

Error: Permission denied - /usr/local/share/man/man5/png.5

E depois disso quando tentobrew link graphicsmagick Eu recebo:

Linking /usr/local/Cellar/graphicsmagick/1.3.18... Warning: Could not link graphicsmagick. Unlinking...

Error: Could not symlink file: /usr/local/Cellar/graphicsmagick/1.3.18/share/man/man5/quantize.5
/usr/local/share/man/man5 is not writable. You should change its permissions.

Por favor me ajude. Desde já, obrigado.