Regular Expression search and replace with 2 conditions

I want to do a search and replace within a file.

The search will be for a filename (within a text file) that its extension is .xml. Find the location by the .xml extension and change the text right before it.

i.e, f开发者_如何转开发ind this line with "emission_mazda_3_c1_zjz6_16_05_ho2s_front.xml" text and replace the text to "emission_mazda_3_c1_zjz6_16_04_ho2s_front.xml".

Any help will be appreciated, Thanks Tommy

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It depends slightly on what you are using the regex in, so I have given a couple of examples.

Using BRE you could use:

s/\(emission_mazda_3_c1_zjz6_16_\)\(05\)\(_ho2s_front.xml\)/\104\3/

Which as Vim uses BRE, to do this on the whole document would be:

%s/\(emission_mazda_3_c1_zjz6_16_\)\(05\)\(_ho2s_front.xml\)/\104\3/

Or with sed, which also uses BRE, to output to stdout the file input.txt with the replacements made:

sed -e 's/\(emission_mazda_3_c1_zjz6_16_\)\(05\)\(_ho2s_front.xml\)/\104\3/' input.txt

While with ERE you could use:

s/(emission_mazda_3_c1_zjz6_16_)(05)(_ho2s_front.xml)/\104\3/

The trick to all this is the use of backreferences. The text between the first two / characters describes what you are looking for and is grouped by using the () characters. The text between the last two / characters is what you want to replace it with. So you are saying replace the found text with the first group (\1 signifies this), then put 04, then add the third group (\3 signifies this).