Then again, sed works differently on different platforms, and awk is not the same as gawk or nawk, both of which have many more features than standard awk. If you're used to the GNU implementation, you might be surprised to find your script doesn't work on a system without the gawk implementation.
On Linux, I can use this sed command: sed -i ‘s/^”//’ example.txt
That deletes any quotation marks that are at the beginning of a line. It does it in-place, and while you have the option to rename the old file and replace it with a new file with the original name (using "sed -i.bak ‘s/^”//’ example.txt" would move the existing example.txt file to example.txt.bak and write a new one in-place), if you leave out the .bak, it just writes it in-place with no backup file.
On OS X, though, that command won't work. You have to specify a backup file, even if it's blank. "sed -i “” ‘s/^”//’ example.txt" would replace the text in-place without a backup. sed -i “.bak” ‘s/^”//’ example.txt would replace the file and move the original to "example.txt.bak".
Even with sed and awk, you still have to stop and wonder if it will work cross-platform.