Here are some one-liners to delete a line or replace a portion of a line in a file. The command line options are explained in perlrun

    # Remove the third line in the file
    perl -i.bak -ne 'print unless $. == 3' file

    # Remove any lines that contain foo
    perl -i.bak -ne 'print unless /foo/' file

    # Remove foo from all lines
    perl -i.bak -pe 's/foo//g' file

    # Substitute foo with bar on all lines
    perl -i.bak -pe 's/foo/bar/g' file
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The -i.bak option makes the changes in-place and saves a back-up to file.bak. If you are sure that your filter is correct you can omit the .bak part and skip the backup (use with care).

--
John.