In mercurial, how do I apply a reverse-patch to a particular file?

Question

Related to Mercurial: Merging one file between branches in one repo , I\'m trying to perform a backout operation on a single file, even though that file was one of many particip

Answer 1

You can do it using just the -I (include names matching the given patterns) argument for backout with a single line:

hg backout --merge -I thefiletorevert -m 'message' OFFENDINGREVISIONID

Example Script:

hg init testrepo
cd testrepo
echo -e "line1\n\nline3" > file1
echo -e "line1\n\nline3" > file2
hg commit -A -m 'changes to two files'
perl -pi -e 's/line1/line 1/' file1
perl -pi -e 's/line1/line 1/' file2
hg commit -m 'put spaces in line1'
perl -pi -e 's/line3/line 3/' file1
perl -pi -e 's/line3/line 3/' file2
hg commit -m 'put spaces in line3'
hg backout --merge -I file1 -m 'remove spaces from line1' 1

Sample output:

adding file1
adding file2
reverting file1
created new head
changeset 3:6d354f1ad4c5 backs out changeset 1:906bbeaca6a3
merging with changeset 3:6d354f1ad4c5
merging file1
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)

Resulting File Contents:

file1:line1
file1:line 3
file2:line 1
file2:line 3

notice that file1 is missing it's space in line one after the backout of the middle changeset, and the verbose log shows only one file changed in the backout:

$ hg log -v -r tip
changeset:   3:6d354f1ad4c5
tag:         tip
parent:      1:906bbeaca6a3
user:        Ry4an Brase 
date:        Mon Sep 14 12:17:23 2009 -0500
files:       file1
description:
remove spaces from line1