From 559e4d7a0d2e98e887ac93c78631d3eeef378716 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Mon, 29 Jan 2007 01:31:35 -0500 Subject: [PATCH] user-manual: reflogs, other recovery Add a brief discussion of reflogs. Also recovery of dangling commits seems to fit in here, so move some of the discussion out of Linus's email to here. Signed-off-by: "J. Bruce Fields" --- Documentation/user-manual.txt | 93 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 78 insertions(+), 15 deletions(-) diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt index 11497b7b62..be5a1f4c10 100644 --- a/Documentation/user-manual.txt +++ b/Documentation/user-manual.txt @@ -1412,10 +1412,82 @@ For more about dangling objects, see <>. Recovering lost changes ~~~~~~~~~~~~~~~~~~~~~~~ -TODO: - reflog - git-fsck - low-level examination of objects +Reflogs +^^^^^^^ + +Say you modify a branch with gitlink:git-reset[1] --hard, and then +realize that the branch was the only reference you had to that point in +history. + +Fortunately, git also keeps a log, called a "reflog", of all the +previous values of each branch. So in this case you can still find the +old history using, for example, + +------------------------------------------------- +$ git log master@{1} +------------------------------------------------- + +This lists the commits reachable from the previous version of the head. +This syntax can be used to with any git command that accepts a commit, +not just with git log. Some other examples: + +------------------------------------------------- +$ git show master@{2} # See where the branch pointed 2, +$ git show master@{3} # 3, ... changes ago. +$ gitk master@{yesterday} # See where it pointed yesterday, +$ gitk master@{"1 week ago"} # ... or last week +------------------------------------------------- + +The reflogs are kept by default for 30 days, after which they may be +pruned. See gitlink:git-reflink[1] and gitlink:git-gc[1] to learn +how to control this pruning, and see the "SPECIFYING REVISIONS" +section of gitlink:git-rev-parse[1] for details. + +Note that the reflog history is very different from normal git history. +While normal history is shared by every repository that works on the +same project, the reflog history is not shared: it tells you only about +how the branches in your local repository have changed over time. + +Examining dangling objects +^^^^^^^^^^^^^^^^^^^^^^^^^^ + +In some situations the reflog may not be able to save you. For +example, suppose you delete a branch, then realize you need the history +it pointed you. The reflog is also deleted; however, if you have not +yet pruned the repository, then you may still be able to find +the lost commits; run git-fsck and watch for output that mentions +"dangling commits": + +------------------------------------------------- +$ git fsck +dangling commit 7281251ddd2a61e38657c827739c57015671a6b3 +dangling commit 2706a059f258c6b245f298dc4ff2ccd30ec21a63 +dangling commit 13472b7c4b80851a1bc551779171dcb03655e9b5 +... +------------------------------------------------- + +and watch for output that mentions "dangling commits". You can examine +one of those dangling commits with, for example, + +------------------------------------------------ +$ gitk 7281251ddd --not --all +------------------------------------------------ + +which does what it sounds like: it says that you want to see the commit +history that is described by the dangling commit(s), but not the +history that is described by all your existing branches and tags. Thus +you get exactly the history reachable from that commit that is lost. +(And notice that it might not be just one commit: we only report the +"tip of the line" as being dangling, but there might be a whole deep +and complex commit history that was gotten dropped.) + +If you decide you want the history back, you can always create a new +reference pointing to it, for example, a new branch: + +------------------------------------------------ +$ git branch recovered-branch 7281251ddd +------------------------------------------------ + Sharing development with others =============================== @@ -2756,22 +2828,13 @@ you recover your old tree (say, you did a rebase, and realized that you really didn't want to - you can look at what dangling objects you have, and decide to reset your head to some old dangling state). -For commits, the most useful thing to do with dangling objects tends to be -to do a simple +For commits, the most useful thing to do with dangling objects tends to +be to do a simple ------------------------------------------------ $ gitk --not --all ------------------------------------------------ -which means exactly what it sounds like: it says that you want to see the -commit history that is described by the dangling commit(s), but you do NOT -want to see the history that is described by all your branches and tags -(which are the things you normally reach). That basically shows you in a -nice way what the dangling commit was (and notice that it might not be -just one commit: we only report the "tip of the line" as being dangling, -but there might be a whole deep and complex commit history that has gotten -dropped - rebasing will do that). - For blobs and trees, you can't do the same, but you can examine them. You can just do -- 2.11.4.GIT