How to modify a specified commit

Question

I usually submit a list of commits for review  If I have the following commits    HEAD Commit3   Commit2   Commit1      I know that I can modify head commit with git commit --amend  But how can I modify Commit1  given that it is not the HEAD commit

User · Answer

Well  this solution might sound very silly  but can save you in certain conditions   A friend of mine just ran into accidentally committing very some huge files  four auto-generated files ranging between 3GB to 5GB each  and then made some additional code commits on top of that before realizing the problem that git push wasn t working any longer     The files had been listed in  gitignore but after renaming the container folder  they got exposed and committed   And now there were a few more commits of the code on top of that  but push was running forever  trying to upload GB of data   and finally would fail due to Github s file size limits   The problem with interactive rebase or anything similar was that they would deal with poking around these huge files and would take forever to do anything   Nevertheless  after spending almost an hour in the CLI  we weren t sure if the files  and deltas  are actually removed from the history or simply not included in the current commits   The push wasn t working either and my friend was really stuck   So  the solution I came up with was    Rename current git folder to   Project-old  Clone the git folder again from github  to   Project     Checkout to the same branch  Manually cp -r the files from   Project-old folder to   Project    Make sure the massive files  that are not needed to be checked in are mved  and included in  gitignore properly    Also make sure you don t overwrite  git folder in the recently-cloned   Project by the old one   That s where the logs of the problematic history lives  Now review the changes   It should be the union of all the recent commits  excluding the problematic files  Finally commit the changes  and it s good to be push ed    The biggest problem with this solution is  it deals with manual copying some files  and also it merges all the recent commits into one  obviously with a new commit-hash    B  The big benefits are that  it is very clear in every step  it works great for huge files  as well as sensitive ones   and it doesn t leave any trace in history behind

User · Answer

Based on Documentation  Amending the message of older or multiple commit messages  git rebase -i HEAD 3    The above displays a list of the last 3 commits on the current branch  change 3 to something else if you want more  The list will look similar to the following   pick e499d89 Delete CNAME pick 0c39034 Better README pick f7fde4a Change the commit message but push the same commit    Replace pick with reword before each commit message you want to change  Let say you change the second commit in the list  your file will look like the following   pick e499d89 Delete CNAME reword 0c39034 Better README pick f7fde4a Change the commit message but push the same commit    Save and close the commit list file  this will pop up a new editer for you to change your commit message  change the commit message and save   Finaly Force-push the amended commits    git push --force

User · Answer

The best option is to use  Interactive rebase command        The git rebase command is incredibly powerful  It allows you to edit   commit messages  combine commits  reorder them    etc        Every time you rebase a commit a new SHA will be created for each   commit regardless of the content will be changed or not  You should be   careful when to use this command cause it may have drastic   implications especially if you work in collaboration with other   developers  They may start working with your commit while you re   rebasing some  After you force to push the commits they will be out of   sync and you may find out later in a messy situation  So be careful       It s recommended to create a backup branch before rebasing so   whenever you find things out of control you can return back to the   previous state    Now how to use this command   git rebase -i  lt base gt     -i stand for  interactive   Note that you can perform a rebase in non-interactive mode  ex    interactivly rebase the n commits from the current position  n is a given number 2 3    etc  git rebase -i HEAD n    HEAD indicates your current location can be also branch name or commit SHA   The  n means  n before    so HEAD n will be the list of  n  commits before the one you are currently on    git rebase has different command like    p or pick to keep commit as it is  r or reword  to keep the commit s content but alter the commit message   s or squash  to combine this commit s changes into the previous commit the commit above it in the list       etc   Note  It s better to get Git working with your code editor to make things simpler  Like for example if you use visual code you can add like this git config --global core editor  code --wait   Or you can search in Google how to associate you preferred your code editor with GIT    Example of git rebase  I wanted to change the last 2 commits I did so I process like this    Display the current commits     This to show all the commits on one line  git log --oneline 4f3d0c8  HEAD - gt  documentation  docs  Add project description and included files  4d95e08 docs  Add created date and project title  eaf7978  origin master   origin HEAD  master  Inital commit 46a5819 Create README md  Now I use git rebase to change the 2 last commits messages   git rebase -i HEAD 2 It opens the code editor and show this   pick 4d95e08 docs  Add created date and project title pick 4f3d0c8 docs  Add project description and included files    Rebase eaf7978  4f3d0c8 onto eaf7978  2 commands      Commands    p  pick  lt commit gt    use commit   r  reword  lt commit gt    use commit  but edit the commit message       Since I want to change the commit message for this 2 commits  So I will type r or reword in place of pick  Then Save the file and close the tab   Note that rebase is executed in a multi-step process so the next step is to update the messages  Note also that the commits are displayed in reverse chronological order so the last commit is displayed in that one and the first commit in the first line and so forth  Update the messages   Update the first message   docs  Add created date and project title to the documentation  README md     Please enter the commit message for your changes  Lines starting   with     will be ignored  and an empty message aborts the commit        save and close Edit the second message  docs  Add project description and included files to the documentation  README md     Please enter the commit message for your changes  Lines starting   with     will be ignored  and an empty message aborts the commit        save and close  You will get a message like this by the end of the rebase  Successfully rebased and updated refs heads documentation which means that you succeed  You can display the changes   5dff827  HEAD - gt  documentation  docs  Add project description and included files to the documentation  README md  4585c68 docs  Add created date and project title to the documentation  README md  eaf7978  origin master  origin HEAD  master  Inital commit 46a5819 Create README md   I wish that may help the new users

User · Answer

If you haven t already pushed the commits then you can go back to a previous commit using git reset HEAD  1 2 3 4      For example  git commit  lt file1 gt  -m  Updated files 1 and 2  git commit  lt file3 gt  -m  Updated file 3    Oops  forgot to add file2 to the first commit     git reset HEAD 1    because I only need to go back 1 commit  git add  lt file2 gt    This will add file2 to the first commit

User · Answer

Use the awesome interactive rebase  git rebase -i   9     Show the last 9 commits in a text editor  Find the commit you want  change pick to e  edit   and save and close the file  Git will rewind to that commit  allowing you to either   use git commit --amend to make changes  or use git reset    to discard the last commit  but not the changes to the files  i e  take you to the point you were at when you d edited the files  but hadn t committed yet    The latter is useful for doing more complex stuff like splitting into multiple commits  Then  run git rebase --continue  and Git will replay the subsequent changes on top of your modified commit  You may be asked to fix some merge conflicts  Note    is shorthand for HEAD  and   is the commit before the specified commit  Read more about rewriting history in the Git docs   Don t be afraid to rebase ProTip        Don t be afraid to experiment with  quot dangerous quot  commands that rewrite history      Git doesn t delete your commits for 90 days by default  you can find them in the reflog    git reset   3     go back 3 commits   git reflog c4f708b HEAD  0   reset  moving to   3 2c52489 HEAD  1   commit  more changes 4a5246d HEAD  2   commit  make important changes e8571e4 HEAD  3   commit  make some changes     earlier commits       git reset 2c52489     and you re back where you started    Watch out for options like --hard and --force though     they can discard data     Also  don t rewrite history on any branches you re collaborating on    On many systems  git rebase -i will open up Vim by default  Vim doesn t work like most modern text editors  so take a look at how to rebase using Vim  If you d rather use a different editor  change it with git config --global core editor your-favorite-text-editor

User · Answer

To get a non-interactive command  put a script with this content in your PATH      bin sh     git-fixup   Use staged changes to modify a specified commit set -e cmt   git rev-parse  1  git commit --fixup   cmt  GIT EDITOR true git rebase -i --autosquash   cmt 1    Use it by staging your changes  with git add  and then run git fixup  lt commit-to-modify gt   Of course  it will still be interactive if you get conflicts

User · Answer

If for some reason you don t like interactive editors  you can use git rebase --onto   Say you want to modify Commit1  First  branch from before Commit1   git checkout -b amending  commit before Commit1    Second  grab Commit1 with cherry-pick   git cherry-pick Commit1   Now  amend your changes  creating Commit1    git add     git commit --amend -m  new message for Commit1    And finally  after having stashed any other changes  transplant the rest of your commits up to master on top of your new commit   git rebase --onto amending Commit1 master   Read   rebase  onto the branch amending  all commits between Commit1  non-inclusive  and master  inclusive    That is  Commit2 and Commit3  cutting the old Commit1 out entirely  You could just cherry-pick them  but this way is easier   Remember to clean up your branches   git branch -d amending

User · Answer

Interactive rebase with --autosquash is something I frequently use when I need to fixup previous commits deeper in the history  It essentially speeds up the process that ZelluX s answer illustrates  and is especially handy when you have more than one commit you need to edit   From the documentation      --autosquash      When the commit log message begins with  squash         or  fixup          and there is a commit whose title begins with the same       automatically modify the todo list of rebase -i so that the commit marked for squashing comes right after the commit to be modified   Assume you have a history that looks like this     git log --graph --oneline   b42d293 Commit3   e8adec4 Commit2   faaf19f Commit1   and you have changes that you want to amend to Commit2 then commit your changes using    git commit -m  fixup  Commit2    alternatively you can use the commit-sha instead of the commit message  so  fixup  e8adec4 or even just a prefix of the commit message   Then initiate an interactive rebase on the commit before    git rebase e8adec4  -i --autosquash   your editor will open with the commits already correctly ordered  pick e8adec4 Commit2 fixup 54e1a99 fixup  Commit2 pick b42d293 Commit3   all you need to do is save and exit

User · Answer

Came to this approach  and it is probably exactly the same as using interactive rebase  but for me it s kind of straightforward   Note  I present this approach for the sake of illustration of what you can do rather than an everyday alternative  Since it has many steps  and possibly some caveats    Say you want to change commit 0 and you are currently on feature-branch  some-commit---0---1---2--- feature-branch HEAD   Checkout to this commit and create a quick-branch  You can also clone your feature branch as a recovery point  before starting      git checkout -b feature-branch-backup  git checkout 0 git checkout -b quick-branch   You will now have something like this   0 quick-branch HEAD---1---2--- feature-branch    Stage changes  stash everything else   git add   example txt git stash   Commit changes and checkout back to feature-branch  git commit --amend git checkout feature-branch   You will now have something like this   some-commit---0---1---2--- feature-branch HEAD                           ---0  quick-branch    Rebase feature-branch onto quick-branch  resolve any conflicts along the way   Apply stash and remove quick-branch   git rebase quick-branch git stash pop git branch -D quick-branch   And you end up with   some-commit---0 ---1 ---2 ---HEAD feature-branch    Git will not duplicate  although I can t really say to what extent  the 0 commit when rebasing   Note  all commit hashes are changed starting from the commit we originally intended to change

User · Answer

Run     git rebase --interactive commit hash   each   indicates how many commits back you want to edit  if it s only one  the commit hash that you specified   then you just add one     Using Vim you change the words pick to reword for the commits you want to change  save and quit  wq   Then git will prompt you with each commit that you marked as reword so you can change the commit message   Each commit message you have to save and quit  wq  to go to the next commit message  If you want to exit without applying the changes  press  q   EDIT  to navigate in vim you use j to go up  k to go down  h to go left  and l to go right  all this in NORMAL mode  press ESC to go to NORMAL mode    To edit a text  press i so that you enter the INSERT mode  where you insert text   Press ESC to go back to NORMAL mode     UPDATE  Here s a great link from github listing How to undo  almost  anything with git

User · Answer

You can use git rebase  For example  if you want to modify commit bbc643cd  run    git rebase --interactive  bbc643cd     Please note the caret   at the end of the command  because you need actually to rebase back to the commit before the one you wish to modify   In the default editor  modify pick to edit in the line mentioning  bbc643cd    Save the file and exit  git will interpret and automatically execute the commands in the file  You will find yourself in the previous situation in which you just had created commit bbc643cd   At this point  bbc643cd is your last commit and you can easily amend it  make your changes and then commit them with the command     git commit --all --amend --no-edit   After that  type     git rebase --continue   to return back to the previous HEAD commit   WARNING  Note that this will change the SHA-1 of that commit as well as all children -- in other words  this rewrites the history from that point forward  You can break repos doing this if you push using the command git push --force

User · Answer

git stash   rebase automation  For when I need to modify an old commit a lot of times for Gerrit reviews  I ve been doing   git-amend-old         Stash  apply to past commit  and rebase the current branch on to of the result    current branch    git rev-parse --abbrev-ref HEAD     apply to   1    git stash   git checkout   apply to    git stash apply   git add -u   git commit --amend --no-edit   new sha    git log --format   H  -n 1     git checkout   current branch    git rebase --onto   new sha    apply to      GitHub upstream   Usage    modify source file  no need to git add if already in repo git-amend-old  old sha   I like this over --autosquash as it does not squash other unrelated fixups

User · Answer

Completely non-interactive command 1  I just thought I d share an alias that I m using for this  It s based on non-interactive interactive rebase  To add it to your git  run this command  explanation given below   git config --global alias amend-to   f     SHA  git rev-parse  quot  1 quot    git commit --fixup  quot  SHA quot   amp  amp  GIT SEQUENCE EDITOR true git rebase --interactive --autosquash  quot  SHA  quot      f   Or  a version that can also handle unstaged files  by stashing and then un-stashing them   git config --global alias amend-to   f     SHA  git rev-parse  quot  1 quot    git stash -k  amp  amp  git commit --fixup  quot  SHA quot   amp  amp  GIT SEQUENCE EDITOR true git rebase --interactive --autosquash  quot  SHA  quot   amp  amp  git stash pop     f   The biggest advantage of this command is the fact that it s no-vim    1 given that there are no conflicts during rebase  of course Usage git amend-to  lt REV gt    e g  git amend-to HEAD 1 git amend-to aaaa1111  The name amend-to seems appropriate IMHO  Compare the flow with --amend  git add    amp  amp  git commit --amend --no-edit   vs git add    amp  amp  git amend-to  lt REV gt   Explanation  git config --global alias  lt NAME gt     lt COMMAND gt   - creates a global git alias named  lt NAME gt  that will execute non-git command  lt COMMAND gt  f      lt BODY gt     f - an  quot anonymous quot  bash function  SHA  git rev-parse  quot  1 quot    - converts the argument to git revision  and assigns the result to variable SHA git commit --fixup  quot  SHA quot  - fixup-commit for SHA  See git-commit docs GIT SEQUENCE EDITOR true git rebase --interactive --autosquash  quot  SHA  quot   git rebase --interactive  quot  SHA  quot  part has been covered by other answers  --autosquash is what s used in conjunction with git commit --fixup  see git-rebase docs for more info GIT SEQUENCE EDITOR true is what makes the whole thing non-interactive  This hack I learned from this blog post

User · Answer

For me it was for removing some credentials from a repo  I tried rebasing and ran into a ton of seemingly unrelated conflicts along the way when trying to rebase --continue  Don t bother attempting to rebase yourself  use the tool called BFG  brew install bfg  on mac

User · Answer

I solved this   1  by creating new commit with changes i want    r8gs4r commit 0   2  i know which commit i need to merge with it  which is commit 3   so  git rebase -i HEAD 4   4 represents recent 4 commit  here commit 3 is in 4th place   3  in interactive rebase recent commit will located at bottom  it will looks alike   pick q6ade6 commit 3 pick vr43de commit 2 pick ac123d commit 1 pick r8gs4r commit 0   4  here we need to rearrange commit if you want to merge with specific one  it should be like   parent   child  pick q6ade6 commit 3 f r8gs4r commit 0 pick vr43de commit 2 pick ac123d commit 1   after rearrange you need to replace p pick with f  fixup will merge without commit message  or s  squash merge with commit message can change in run time   and then save your tree   now merge done with existing commit      Note  Its not preferable method unless you re maintain on your own  if   you have big team size its not a acceptable method to rewrite  git   tree will end up in conflicts which you know other wont  if you want   to maintain you tree clean with less commits can try this and if its   small team otherwise its not preferable

User · Answer

Automated interactive rebase edit followed by commit revert  ready for a do-over  I found myself fixing a past commit frequently enough that I wrote a script for it    Here s the workflow    git commit-edit  lt commit-hash gt    This will drop you at the commit you want to edit  Fix and stage the commit as you wish it had been in the first place    You may want to use git stash save to keep any files you re not committing  Redo the commit with --amend  eg   git commit --amend  Complete the rebase   git rebase --continue    For the above to work  put the below script into an executable file called git-commit-edit somewhere in your  PATH        bin bash  set -euo pipefail  script name   0       warn      printf   s   s n    script name        gt  amp 2    die      warn       exit 1           -ge 2     amp  amp  die  Expected single commit to edit  Defaults to HEAD      Default to editing the parent of the most recent commit   The most recent commit can be edited with  git commit --amend  commit   git rev-parse --short    1 -HEAD     message   git log -1 --format   h  s    commit    if     OSTYPE     darwin     then   sed inplace  sed -Ei     else   sed inplace  sed -Ei  fi  export GIT SEQUENCE EDITOR    sed inplace         s  pick     commit       edit   1    git rebase --quiet --interactive --autostash --autosquash   commit   git reset --quiet       git rev-parse --show-toplevel      Reset the cache of the toplevel directory to the previous commit git commit --quiet --amend --no-edit --allow-empty     Commit an empty commit so that that cache diffs are un-reversed  echo echo  Editing commit   message   gt  amp 2 echo

[git] How to modify a specified commit?

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