How to replace file strings with regexp in Linux [migrated]

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http://stackoverflow.com – I'm trying to replace the specific numbers and use this command: sed -e 's/[0-9]\{12\}/ /g' file.log but nothing happens. As U can see this expression should replace all numeric occurrences with size of 12 digits, globally and replace it with space. I found out that the {, } symbols should be escaped - weird. It doesn't work. Please help. (HowTos)