Why does git revert complain about a missing -m option

Question

So I m working on a project with other people  and there s multiple github forks being worked on  Someone just made a fix for a problem and I merged with his fork  but then I realized that I could find a better solution  I want to revert the commit I just made  I tried doing this with git revert HEAD but it gave me this error    fatal  Commit  lt SHA1  is a merge but no -m option was given   What does that mean  When I merged and committed  I did use the -m option to say  Merged with  lt username     What am I doing wrong here

User · Answer

By default git revert refuses to revert a merge commit as what that actually means is ambiguous  I presume that your HEAD is in fact a merge commit   If you want to revert the merge commit  you have to specify which parent of the merge you want to consider to be the main trunk  i e  what you want to revert to   Often this will be parent number one  for example if you were on master and did git merge unwanted and then decided to revert the merge of unwanted  The first parent would be your pre-merge master branch and the second parent would be the tip of unwanted   In this case you could do   git revert -m 1 HEAD

User · Answer

I had this problem  the solution was to look at the commit graph  using gitk  and see that I had the following       commit I want to cherry-pick  x           branch I want to cherry-pick to  y              common parent  x    I understand now that I want to do   git cherry-pick -m 2 mycommitsha   This is because -m 1 would merge based on the common parent where as -m 2 merges based on branch y  that is the one I want to cherry-pick to

User · Answer

Say the other guy created bar on top of foo  but you created baz in the meantime and then merged  giving a history of    git lola     2582152  HEAD  master  Merge branch  otherguy           c7256de  otherguy  bar     b7e7176 baz        9968f79 foo  Note  git lola is a non-standard but useful alias   No dice with git revert     git revert HEAD fatal  Commit 2582152    is a merge but no -m option was given   Charles Bailey gave an excellent answer as usual  Using git revert as in    git revert --no-edit -m 1 HEAD  master e900aad  Revert  Merge branch  otherguy    0 files changed  0 insertions     0 deletions -   delete mode 100644 bar  effectively deletes bar and produces a history of    git lola   e900aad  HEAD  master  Revert  Merge branch  otherguy       2582152 Merge branch  otherguy           c7256de  otherguy  bar     b7e7176 baz        9968f79 foo  But I suspect you want to throw away the merge commit     git reset --hard HEAD  HEAD is now at b7e7176 baz    git lola   b7e7176  HEAD  master  baz     c7256de  otherguy  bar        9968f79 foo  As documented in the git rev-parse manual      lt rev gt    e g  HEAD   v1 5 1 0   A suffix   to a revision parameter means the first parent of that commit object    lt n gt  means the n-th parent  i e   lt rev gt   is equivalent to  lt rev gt  1   As a special rule   lt rev gt  0 means the commit itself and is used when  lt rev gt  is the object name of a tag object that refers to a commit object    so before invoking git reset  HEAD   or HEAD 1  was b7e7176 and HEAD 2 was c7256de  i e   respectively the first and second parents of the merge commit   Be careful with git reset --hard because it can destroy work

[git] Why does git revert complain about a missing -m option?

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