C:\test>del junk.in && ren junk.in.org junk.in

C:\test>type junk.in
-i[*extension*]
     If the extension doesn't contain a "*", then it is appended to the
     end of the current filename as a suffix. If the extension does
     contain one or more "*" characters, then each "*" is replaced with
     the current filename. In Perl terms, you could think of this as:

         ($backup = $extension) =~ s/\*/$file_name/g;

     This allows you to add a prefix to the backup file, instead of (or
     in addition to) a suffix:
<!- BRS -->
         $ perl -pi 'orig_*' -e 's/bar/baz/' fileA   # backup to 'orig_fileA'
<!- ERS -->
     Or even to place backup copies of the original files into another
     directory (provided the directory already exists):

         $ perl -pi 'old/*.orig' -e 's/bar/baz/' fileA # backup to 'old/fileA.orig'
<!- BRS -->

    These sets of one-liners are equivalent:
<!- ERS -->
         $ perl -pi -e 's/bar/baz/' fileA            # overwrite current file
         $ perl -pi '*' -e 's/bar/baz/' fileA        # overwrite current file

         $ perl -pi '.orig' -e 's/bar/baz/' fileA    # backup to 'fileA.orig'
         $ perl -pi '*.orig' -e 's/bar/baz/' fileA   # backup to 'fileA.orig'


C:\test>test -B=BRS -E=ERS -R="Replacement text" junk.in

C:\test>type junk.in
-i[*extension*]
     If the extension doesn't contain a "*", then it is appended to the
     end of the current filename as a suffix. If the extension does
     contain one or more "*" characters, then each "*" is replaced with
     the current filename. In Perl terms, you could think of this as:

         ($backup = $extension) =~ s/\*/$file_name/g;

     This allows you to add a prefix to the backup file, instead of (or
     in addition to) a suffix:
Replacement text
     Or even to place backup copies of the original files into another
     directory (provided the directory already exists):

         $ perl -pi 'old/*.orig' -e 's/bar/baz/' fileA # backup to 'old/fileA.orig'
Replacement text
         $ perl -pi -e 's/bar/baz/' fileA            # overwrite current file
         $ perl -pi '*' -e 's/bar/baz/' fileA        # overwrite current file

         $ perl -pi '.orig' -e 's/bar/baz/' fileA    # backup to 'fileA.orig'
         $ perl -pi '*.orig' -e 's/bar/baz/' fileA   # backup to 'fileA.orig'