git merge after git cherry-pick: avoiding duplicate commits

Sat, 2008-09-27

Imagine we have the master branch and a branch b:

  o---X   <-- master
    b1---b2---b3---b4   <-- b

Now we urgently need the commits b1 and b3 in master, but not the remaining commits in b. So what we do is checkout the master branch and cherry-pick commits b1 and b3:

$ git checkout master
$ git cherry-pick “b1’s SHA”
$ git cherry-pick “b3’s SHA”

The result would be:

  o---X---b1'---b3'   <-- master
    b1---b2---b3---b4   <-- b

Let’s say we do another commit on master and we get:

  o---X---b1'---b3'---Y   <-- master
    b1---b2---b3---b4   <-- b

If we would now merge branch b into master:

$ git merge b

We would get the following:

  o---X---b1'---b3'---Y--- M  <-- master
   \                     /
     b1----b2----b3----b4   <-- b

That means the changes introduced by b1 and b3 would appear twice in the history. To avoid that we can rebase instead of merge:

$ git rebase master b

Which would yield:

  o---X---b1'---b3'---Y   <-- master
                        b2---b4   <-- b


$ git checkout master
$ git merge b

gives us:

  o---X---b1'---b3'---Y---b2---b4   <-- master, b



Bash extended pattern matching

Sun, 2008-09-14

If you don’t have extended pattern matching enabled you can enable it with shopt -s extglob

From the bash manual page:

If the extglob shell option is enabled using the shopt builtin, several
extended pattern matching operators are recognized. In the following
description, a pattern-list is a list of one or more patterns separated
by a |. Composite patterns may be formed using one or more of the fol‐
lowing sub-patterns:

Matches zero or one occurrence of the given patterns
Matches zero or more occurrences of the given patterns
Matches one or more occurrences of the given patterns
Matches one of the given patterns
Matches anything except one of the given patterns


$ touch abc1d abc2d abcd abc11d abc3d
$ ls
abc11d abc1d abc2d abc3d abcd
$ ls abc?(1|2)d
abc1d abc2d abcd
$ ls abc*(1|2)d
abc11d abc1d abc2d abcd
$ ls abc+(1|2)d
abc11d abc1d abc2d
$ ls abc@(1|2)d
abc1d abc2d
$ ls abc!(1|2)d
abc11d abc3d abcd

Merging with vimdiff

Thu, 2008-09-11
Open the files with vimdiff:
$ vimdiff file1 file2

To jump to the next difference:

To jump to the previous difference:

If there are only two files you can copy differences with:

If you are doing a diff with vim between more than two files you also have to specify from which buffer to :diffget or from which buffer to :diffput
:diffget b#
where b# is the buffer number. In vertical window split, buffers are numbered from left to right starting at 1.