Sep 22

This post is very useful if you have ever needed to make a readonly mac .dmg file writable. Say for instance that you wanted to create a Mac OS X install disk, then mount it up writable, add something to it and then save it to be used to install OS X in say “VMware”. Listed below are the steps to make this happen:

From Terminal:
###This creates a writable dmg image###
hdiutil convert nameoffile.dmg -format UDRW -o nameoffile_writable.dmg

###This tells you the size of the image###
hdiutil resize -limits nameoffile_writable.dmg

###This resizes your dmg image so that you will have space to add stuff to it. Make sure you substitute the first number from the previous command and add to it sufficiently for the 9999etc. number###
hdiutil resize -sectors 999999 nameoffile_writable.dmg

###This mounts the new dmg writable image so that you can add stuff to it###
hdiutil attach nameoffile_writable.dmg






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