git-replace(1) [linux man page]

GIT-REPLACE(1)							    Git Manual							    GIT-REPLACE(1)

NAME

       git-replace - Create, list, delete refs to replace objects

SYNOPSIS

       git replace [-f] <object> <replacement>
       git replace -d <object>...
       git replace -l [<pattern>]

DESCRIPTION

       Adds a replace reference in refs/replace/ namespace.

       The name of the replace reference is the SHA-1 of the object that is replaced. The content of the replace reference is the SHA-1 of the
       replacement object.

       The replaced object and the replacement object must be of the same type. This restriction can be bypassed using -f.

       Unless -f is given, the replace reference must not yet exist.

       There is no other restriction on the replaced and replacement objects. Merge commits can be replaced by non-merge commits and vice versa.

       Replacement references will be used by default by all Git commands except those doing reachability traversal (prune, pack transfer and
       fsck).

       It is possible to disable use of replacement references for any command using the --no-replace-objects option just after git.

       For example if commit foo has been replaced by commit bar:

	   $ git --no-replace-objects cat-file commit foo

       shows information about commit foo, while:

	   $ git cat-file commit foo

       shows information about commit bar.

       The GIT_NO_REPLACE_OBJECTS environment variable can be set to achieve the same effect as the --no-replace-objects option.

OPTIONS

       -f, --force
	   If an existing replace ref for the same object exists, it will be overwritten (instead of failing).

       -d, --delete
	   Delete existing replace refs for the given objects.

       -l <pattern>, --list <pattern>
	   List replace refs for objects that match the given pattern (or all if no pattern is given). Typing "git replace" without arguments,
	   also lists all replace refs.

CREATING REPLACEMENT OBJECTS

       git-filter-branch(1), git-hash-object(1) and git-rebase(1), among other git commands, can be used to create replacement objects from
       existing objects.

       If you want to replace many blobs, trees or commits that are part of a string of commits, you may just want to create a replacement string
       of commits and then only replace the commit at the tip of the target string of commits with the commit at the tip of the replacement string
       of commits.

BUGS

       Comparing blobs or trees that have been replaced with those that replace them will not work properly. And using git reset --hard to go back
       to a replaced commit will move the branch to the replacement commit instead of the replaced commit.

       There may be other problems when using git rev-list related to pending objects.

SEE ALSO

       git-hash-object(1) git-filter-branch(1) git-rebase(1) git-tag(1) git-branch(1) git(1)

GIT

       Part of the git(1) suite

Git 1.8.5.3							    01/14/2014							    GIT-REPLACE(1)

GIT-MERGE-BASE(1)						    Git Manual							 GIT-MERGE-BASE(1)

NAME

       git-merge-base - Find as good common ancestors as possible for a merge

SYNOPSIS

       git merge-base [-a|--all] <commit> <commit>...
       git merge-base [-a|--all] --octopus <commit>...
       git merge-base --independent <commit>...

DESCRIPTION

       git merge-base finds best common ancestor(s) between two commits to use in a three-way merge. One common ancestor is better than another
       common ancestor if the latter is an ancestor of the former. A common ancestor that does not have any better common ancestor is a best
       common ancestor, i.e. a merge base. Note that there can be more than one merge base for a pair of commits.

OPERATION MODE

       As the most common special case, specifying only two commits on the command line means computing the merge base between the given two
       commits.

       More generally, among the two commits to compute the merge base from, one is specified by the first commit argument on the command line;
       the other commit is a (possibly hypothetical) commit that is a merge across all the remaining commits on the command line.

       As a consequence, the merge base is not necessarily contained in each of the commit arguments if more than two commits are specified. This
       is different from git-show-branch(1) when used with the --merge-base option.

       --octopus
	   Compute the best common ancestors of all supplied commits, in preparation for an n-way merge. This mimics the behavior of git
	   show-branch --merge-base.

       --independent
	   Instead of printing merge bases, print a minimal subset of the supplied commits with the same ancestors. In other words, among the
	   commits given, list those which cannot be reached from any other. This mimics the behavior of git show-branch --independent.

OPTIONS

       -a, --all
	   Output all merge bases for the commits, instead of just one.

DISCUSSION

       Given two commits A and B, git merge-base A B will output a commit which is reachable from both A and B through the parent relationship.

       For example, with this topology:

		    o---o---o---B
		   /
	   ---o---1---o---o---o---A

       the merge base between A and B is 1.

       Given three commits A, B and C, git merge-base A B C will compute the merge base between A and a hypothetical commit M, which is a merge
       between B and C. For example, with this topology:

		  o---o---o---o---C
		 /
		/   o---o---o---B
	       /   /
	   ---2---1---o---o---o---A

       the result of git merge-base A B C is 1. This is because the equivalent topology with a merge commit M between B and C is:

		  o---o---o---o---o
		 /		   
		/   o---o---o---o---M
	       /   /
	   ---2---1---o---o---o---A

       and the result of git merge-base A M is 1. Commit 2 is also a common ancestor between A and M, but 1 is a better common ancestor, because 2
       is an ancestor of 1. Hence, 2 is not a merge base.

       The result of git merge-base --octopus A B C is 2, because 2 is the best common ancestor of all commits.

       When the history involves criss-cross merges, there can be more than one best common ancestor for two commits. For example, with this
       topology:

	   ---1---o---A
	        /
		X
	       / 
	   ---2---o---o---B

       both 1 and 2 are merge-bases of A and B. Neither one is better than the other (both are best merge bases). When the --all option is not
       given, it is unspecified which best one is output.

SEE ALSO

       git-rev-list(1), git-show-branch(1), git-merge(1)

GIT

       Part of the git(1) suite

Git 1.7.10.4							    11/24/2012							 GIT-MERGE-BASE(1)