You can do this as a one-liner, too: 
# old: foo.dat.bak   new: foo.dat
perl -i.bak -ne 'print unless /^AB.*C$/' foo.dat
#        OR
# old: foo.dat   new: foo.dat.fixed
perl -ne 'print unless /^AB.*C$/' foo.dat > foo.dat.fixed

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In reply to Re: Writing into files and RegExp by davidrw
in thread Writing into files and RegExp by PerlingTheUK

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