How to find the nearest parent of a Git branch

Question

Let s say I have the following local repository with a commit tree like this   master -- gt  a                                    develop c -- gt  d                                             feature f -- gt  g -- gt  h   master is my this is the latest stable release code  develop is my this is the  next  release code  and feature is a new feature being prepared for develop   What I want to be able to do on my remote repo using hooks  is for pushes to feature to be refused unless commit f is a direct descendant of develop HEAD  i e  the commit tree looks like this because feature has been git rebase on d   master -- gt  a                                    develop c -- gt  d                                                               feature f -- gt  g -- gt  h   So is it possible to    Identify the parent branch of feature  Identify the commit in parent branch which f is a descendant of    From there I would check what HEAD of parent branch is  and see if f predecessor matches the parent branch HEAD  to determine if the feature needs to be rebased

User · Answer

This did not work for me when I had done something like develop > release-v1.0.0 > feature-foo, it would go all the way back to develop, note there was a rebase involved, not sure if that is compounding my issue...

The following did give the correct commit hash for me

git log --decorate \
  | grep 'commit' \
  | grep 'origin/' \
  | head -n 2 \
  | tail -n 1 \
  | awk '{ print $2 }' \
  | tr -d "\n"

User · Answer

You can also try   git log --graph --decorate

User · Answer

git log -2 --pretty format   d  --abbrev-commit   tail -n 1   sed  s  s   g  s    n g      origin parent-name  parent-name    git log -2 --pretty format   d  --abbrev-commit   tail -n 1   sed  s  s   g  s    n g     origin parent-name   git log -2 --pretty format   d  --abbrev-commit   tail -n 1   sed  s       g  s         parent-name

User · Answer

This working fine for me   git show-branch   grep       grep -v    git rev-parse --abbrev-ref HEAD     head -n1   sed  s                 1     sed  s              Courtesy answers from   droidbot and  Jistanidiot

User · Answer

Here s my Powershell Version  function Get-GHAParentBranch        CmdletBinding        param           Name    git branch --show-current            git show-branch          Select-String                      Select-String -NotMatch -Pattern  quot      Regex   Escape  Name        quot          Select-Object -First 1         Foreach-Object   PSItem -replace                     1

User · Answer

Remember that  as described in  Git  Finding what branch a commit came from   you cannot  easily pinpoint the branch where that commit has been made  branches can be renamed  moved  deleted      even though git branch --contains  lt commit gt  is a start    You can go back from commit to commit until git branch --contains  lt commit gt  doesn t list the feature branch and list develop branch  compare that commit SHA1 to  refs heads develop   If the two commits id match  you are good to go  that would mean the feature branch has its origin at the HEAD of develop

User · Answer

Mark Reed  You should add that the commit line should not only contain an asterisk  but begin with an asterisk  Otherwise commit messages that contain an asterisk are also included in the matched lines  So it should be   git show-branch -a   awk -F                 amp  amp       current branch     print  2 exit    or the long version   git show-branch -a               awk                            we want only lines that contain an asterisk   awk -v   current branch        but also don t contain the current branch   head -n1                       and only the first such line   sed  s                 1       really  just the part of the line between      sed  s                         and with any relative refs      n  removed

User · Answer

JoeChrysler s command-line magic can be simplified   Here s Joe s logic - for brevity I ve introduced a parameter named cur branch in place of the command substitution  git rev-parse --abbrev-ref HEAD  into both versions  that can be initialized like so   cur branch   git rev-parse --abbrev-ref HEAD    Then  here s Joe s pipeline   git show-branch -a               grep                           we want only lines that contain an asterisk   grep -v   cur branch           but also don t contain the current branch   head -n1                       and only the first such line   sed  s                 1       really  just the part of the line between      sed  s                         and with any relative refs      n  removed   We can accomplish the same thing as all five of those individual command filters in a relatively simple awk command   git show-branch -a     awk -F                amp  amp       cur branch     print  2 exit       That breaks down like this   -F            split the line into fields at          and   characters                                Find lines that contain an asterisk   amp  amp       cur branch         but not the current branch name    print  2                   When you find such a line  print its second field  that is  the part between the first and second occurrences of our field separator characters   For simple branch names  that will be just what s between the brackets  for refs with relative jumps  it will be just the name without the modifier  So our set of field separators handles the intent of both sed commands     exit     Then exit immediately   This means it only ever processes the first matching line  so we don t need to pipe the output through head -n 1

User · Answer

git parent  You can just run  the command   git parent  to find the parent of the branch  if you add the  Joe Chrysler s answer as a git alias  It will simplify the usage   Open gitconfig file located at     gitconfig  by using any text editor    For linux   And for Windows the    gitconfig  path is generally located at c  users your-user  gitconfig  vim     gitconfig   Add the following alias command in the file     alias              parent     git show-branch   grep       grep -v     git rev-parse --abbrev-ref HEAD      head -n1   sed  s                      1     sed  s                  Save and exit the editor   Run the command  git parent   That s it

User · Answer

A solution  The solution based on git show-branch did not quite work for me  see below   so I ve combined it with the one based on git log and ended up with this   git log --decorate --simplify-by-decoration --oneline     selects only commits with a branch or tag         grep -v   HEAD                                    removes current head  and branch          head -n1                                          selects only the closest decoration         sed  s                 1                          filters out everything but decorations         sed  s             1                              picks only the first decoration         sed  s origin                                     strips  origin   from the decoration   Limitations and Caveats   HEAD can be detached  many CI tools do so to ensure they build correct commit in a given branch   but origin branch and local branch have to be both at par or  above  the current HEAD  There must be no tags in the way  I presume  I have not tested the script on commits with a tag between child and parent branch  the script relies on the fact  HEAD  is always listed as the first decoration by the log command running the script on master and develop results  mostly  in  lt SHA gt  Initial commit   The results   A---B---D---E---F  lt -origin master  master                                               G---H---I  lt - origin hotfix  hotfix                                   J---K---L  lt -origin develop  develop                                                        M---N---O  lt -origin feature a  feature a                                                                                         P---Q---R  lt -origin feature b  feature b                                                                                      S---T---U  lt -origin feature c  feature c   Despite local branch existence  e g  only origin topic is present since the commit O was checked-out by directly by its SHA   the script should print as follows    For commits G  H  I  branch hotfix    master For commits M  N  O  branch feature a    develop For commits S  T  U  branch feature c    develop For commits P  Q  R  branch feature b    feature a For commits J  K  L  branch develop     lt sha gt  Initial commit  For commits B  D  E  F  branch master     lt sha gt  Initial commit     - or master if develop s commits were on top of master s HEAD    the master would be fast-forwardable to develop     Why did not show-branch work for me  The solution based on git show-branch proved unreliable for me in the following situations    detached HEAD     including detached head case means replacing grep        for  grep           and that is just the beginning of all the troubles running the script on master and develop results in develop and    respectively branches on master branch  hotfix  branches  end up with the develop as a parent since their closest master branch parent was marked with   instead of   for a reason

User · Answer

A rephrasal  Another way to phrase the question is  What is the nearest commit that resides on a branch other than the current branch  and which branch is that    A solution  You can find it with a little bit of command line magic  git show-branch     sed  s            grep          grep -v    git rev-parse --abbrev-ref HEAD       head -n1     sed  s             With awk   git show-branch -a     grep          grep -v  git rev-parse --abbrev-ref HEAD      head -n1     sed  s               awk  match  0      a-zA-Z0-9  -         print substr   0  RSTART 1  RLENGTH-2       Here s how it works    Display a textual history of all commits  including remote branches  Ancestors of the current commit are indicated by a star  Filter out everything else  Ignore all the commits in the current branch  The first result will be the nearest ancestor branch  Ignore the other results  Branch names are displayed  in brackets   Ignore everything outside the brackets  and the brackets  Sometimes the branch name will include a    or    to indicate how many commits are between the referenced commit and the branch tip  We don t care  Ignore them    And the Result  Running the above code on   A---B---D  lt -master                          C---E---I  lt -develop                                               F---G---H  lt -topic   Will give you develop if you run it from H and master if you run it from I   The code is available as a gist

User · Answer

Assuming that the remote repository has a copy of the develop branch  your initial description describes it in a local repository  but it sounds like it also exists in the remote   you should be able to achieve what I think you want  but the approach is a bit different from what you have envisioned   Git   s history is based on a DAG of commits  Branches  and    refs    in general  are just transient labels that point to specific commits in the continually growing commit DAG  As such  the relationship between branches can vary over time  but the relationship between commits does not       ---o---1                foo                            2---3---o      bar                                        4                                            5---6  baz   It looks like baz is based on  an old version of  bar  But what if we delete bar       ---o---1                foo                            2---3                                        4                                            5---6  baz   Now it looks like baz is based on foo  But the ancestry of baz did not change  we just removed a label  and the resulting dangling commit   And what if we add a new label at 4       ---o---1                foo                            2---3                                        4        quux                                            5---6  baz   Now it looks like baz is based on quux  Still  the ancestry did not change  only the labels changed   If  however  we were asking    is commit 6 a descendent of commit 3      assuming 3 and 6 are full SHA-1 commit names   then the answer would be    yes     whether the bar and quux labels are present or not   So  you could ask questions like    is the pushed commit a descendent of the current tip of the develop branch      but you can not reliably ask    what is the parent branch of the pushed commit       A mostly reliable question that seems to get close to what you want is      For all the pushed commit   s ancestors  excluding the current tip of develop and its ancestors   that have the current tip of develop as a parent          does at least one such commit exist    are all such commits single-parent commits       Which could be implemented as   pushedrev     basename develop if   baserev    git rev-parse --verify refs heads   basename  2 gt  dev null    then     echo    basename  is missing  call for help       exit 1 fi parents of children of base       git rev-list --pretty tformat  P   pushedrev  --not   baserev      grep -F   baserev     case    parents of children of base  in            echo  must descend from tip of   basename              exit 1               echo  must not merge tip of   basename   rebase instead              exit 1               exit 0    esac   This will cover some of what you want restricted  but maybe not everything   For reference  here is an extended example history       A                                   master                                   o-----J                                                                o---K---L                                       C--------------D              develop                                         F---G---H      F --G --H                                                         o---o---o---N                                                                            o---o---P                                                         R---S   The above code could be used to reject Hand S while accepting H   J  K  or N  but it would also accept L and P  they involve merges  but they do not merge the tip of develop    To also reject L and P  you can change the question and ask     For all the pushed commit   s ancestors  excluding the current tip of develop and its ancestors           are there any commits with two parents    if not  does at least one such commit have the current tip of develop its  only  parent       pushedrev     basename develop if   baserev    git rev-parse --verify refs heads   basename  2 gt  dev null    then     echo    basename  is missing  call for help       exit 1 fi parents of commits beyond base       git rev-list --pretty tformat  P   pushedrev  --not   baserev      grep -v   commit      case   parents of commits beyond base  in                    echo  must not push merge commits  rebase instead                      exit 1           baserev     exit 0                       echo  must descend from tip of   basename                      exit 1    esac

User · Answer

Anyone wanting to do this these days - Atlassian s SourceTree application shows you a great visual representation of how your branches relate to one another  i e  Where they began and where they currently sit in the commit order  e g  HEAD or 4 commits behind  etc

User · Answer

Cross-platform implementation with Ant       lt exec executable  git  outputproperty  currentBranch  gt           lt arg value  rev-parse    gt             lt arg value  --abbrev-ref    gt             lt arg value  HEAD    gt         lt  exec gt        lt exec executable  git  outputproperty  showBranchOutput  gt           lt arg value  show-branch    gt             lt arg value  -a    gt         lt  exec gt        lt loadresource property  baseBranch  gt         lt propertyresource name  showBranchOutput   gt             lt filterchain gt               lt linecontains gt                 lt contains value      gt               lt  linecontains gt               lt linecontains negate  true  gt                 lt contains value    currentBranch    gt               lt  linecontains gt               lt headfilter lines  1   gt               lt tokenfilter gt                   lt replaceregex pattern                replace   1   gt                   lt replaceregex pattern           replace     gt               lt  tokenfilter gt             lt  filterchain gt       lt  loadresource gt        lt echo message    currentBranch    baseBranch     gt

User · Answer

I have a solution to your overall problem  determine if feature is descended from the tip of develop   but it doesn t work using the method you outlined   You can use git branch --contains to list all the branches descended from the tip of develop  then use grep to make sure feature is among them   git branch --contains develop   grep     feature     If it is among them  it will print    feature  to standard output and have a return code of 0      Otherwise  it will print nothing and have a return code of 1

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Git comes with a couple of GUI clients that helps you visualize this  Open GitGUI and go to menu Repository  gt  Visualize All Branch History

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The solutions based on git show-branch -a plus some filters have one downside  git may consider a branch name of a short lived branch  If you have a few possible parents which you care about  you can ask yourself this similar question  and probably the one the OP wanted to know about   From a specific subset of all branches  which is the nearest parent of a git branch  To simplify  I ll consider  quot a git branch quot  to refer to HEAD  i e   the current branch   Let s imagine that we have the following branches  HEAD important a important b spam a spam b  The solutions based on git show-branch -a   filters  may give that the nearest parent of HEAD is spam a  but we don t care about that  If we want to know which of important a and important b is the closest parent of HEAD  we could run the following  for b in   git branch -a -l  quot important   quot    do     d1   git rev-list --first-parent    b  HEAD  wc -l       d2   git rev-list --first-parent  HEAD   b   wc -l       echo  quot   b    d1    d2  quot   done    sort -n -k2 -k3    head -n1    awk   print  1     What it does  1     git branch -a -l  quot important   quot    Print a list of all branches with some pattern   quot important   quot    2   d   git rev-list --first-parent    b  HEAD  wc -l    For each of those branches   b   calculate the distance   d1  in number of commits  from HEAD to the nearest commit in  b  similar to when you calculate the distance from a point to a line    You may want to consider the distance differently here  you may not want to use --first-parent  or may want distance from tip to the tip of the branches   quot   b  quot    HEAD       2 2  d2   git rev-list --first-parent  HEAD   b   wc -l    For each of those branches   b   calculate the distance   d2  in number of commits from the tip of the branch to the nearest commit in HEAD   We will use this distance to choose between two branches whose distance  d1 was equal  3   echo  quot   b    d1    d2  quot    Print the name of each of the branches  followed by the distances to be able to sort them later  first  d1  and then  d2   4    sort -n -k2 -k3  Sort the previous result  so we get a sorted  by distance  list of all of the branches  followed by their distances  both   5    head -n1  The first result of the previous step will be the branch that has a smaller distance  i e   the closest parent branch   So just discard all other branches  6    awk   print  1     We only care about the branch name  and not about the distance  so extract the first field  which was the parent s name   Here it is

User · Answer

vbc   git rev-parse --abbrev-ref HEAD  vbc col       git show-branch   grep               head -1   cut -d  -f1   wc -c  - 1     swimming lane start row       git show-branch   grep -n     -       cut -d  -f1    1     git show-branch   tail -n   swimming lane start row   grep -v            vbc    grep       vbc col          head -n1   sed  s                 1     sed  s              Achieves the same ends as Mark Reed s answer  but uses a much safer approach that doesn t misbehave in a number of scenarios    Parent branch s last commit is a merge  making the column show - not   Commit message contains branch name Commit message contains

User · Answer

I m not saying this is a good way to solve this problem  however this does seem to work-for-me   git branch --contains   cat  git ORIG HEAD  The issue being that cat ing a file is peeking into the inner working of git so this is not necessarily forwards-compatible  or backwards-compatible

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An alternative   git rev-list master   grep    git rev-list HEAD     head -1  Get the last commit that it s both my branch and master  or whatever branch you want to specify

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If you use Source Tree look at your commit details   Parents   then you ll see commit numbers underlined  links

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Since none of the answers above worked on our repository  I want to share my own way  using latest merges in git log      bin bash git log --oneline --merges        grep into   sed  s    into   g    uniq --count   head -n 10   Put it in a script named git-last-merges  which also accepts a branch name as argument  instead of current branch  as well as other git log arguments  From the output  we can manually detect the parent branch es  based on own branching conventions and number of merges from each branch   EDIT  If you use git rebase on child branches often  and merges are fast-forwarded often so there aren t too many merge commits   this answer won t work well  so I wrote a script to count ahead commits  normal and merge   and behind commits  there shouldn t be any behind merge in parent branch  on all branches comparing to the current branch  Just run this script and let me know if works for you or not     bin bash HEAD   git rev-parse --abbrev-ref HEAD   echo  Comparing to  HEAD  printf   12s   12s    10s      s n   Behind   BehindMerge   Ahead   Branch  git branch   grep -v        sed  s       g    while read branch   do     ahead merge count  git log --oneline --merges  branch   HEAD   wc -l      if     ahead merge count    0      then         continue     fi     ahead count  git log --oneline --no-merges  branch   HEAD   wc -l      behind count  git log --oneline --no-merges   branch  HEAD   wc -l      behind merge count  git log --oneline --merges   branch  HEAD   wc -l      behind  - behind count      behind merge  -M behind merge count      ahead    ahead count      printf   12s   12s    10s      s n    behind    behind merge    ahead    branch  done   sort -n

User · Answer

Here is a PowerShell implementation of Mark Reed s solution   git show-branch -a   where-object      Contains      -eq  true    Where-object     Contains  branchName  -ne  true     select -first 1         -replace                  1             -replace

[git] How to find the nearest parent of a Git branch?

Examples related to git

Examples related to branch