Check if pull needed in Git

Question

How do I check whether the remote repository has changed and I need to pull   Now I use this simple script   git pull --dry-run   grep -q -v  Already up-to-date    amp  amp  changed 1   But it is rather heavy   Is there a better way  The ideal solution would check all the remote branches  and return names of the changed branches and the number of new commits in each one

User · Answer

If this is for a script  you can use   git fetch   git rev-parse HEAD       git rev-parse   u      Note  the benefit of this vs  previous answers is that you don t need a separate command to get the current branch name   HEAD  and    u    the current branch s upstream  take care of it  See  git rev-parse --help  for more details

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I would do the way suggested by brool  The following one-line script takes the SHA1 of your last commited version and compares it to the one of the remote origin  and pull changes only if they differ  And it s even more light-weight of the solutions based on git pull or git fetch      git log --pretty  H    refs heads master       git ls-remote origin -h refs heads master  cut -f1     amp  amp  git pull

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If you run this script  it will test if the current branch need a git pull      bin bash  git fetch -v --dry-run 2 gt  amp 1       grep -qE    up s to s date   s            git branch 2 gt  dev null              sed -n       s       p                    sed -r  s               1 g        s                echo  gt  amp 2  Current branch need a  git pull  before commit          exit 1     It s very convenient to put it as a Git hook pre-commit to avoid  Merge branch  foobar  of url  path to git foobar into foobar   when you commit before pulling   To use this code as a hook  simply copy paste the script in   git hooks pre-commit   and  chmod  x  git hooks pre-commit

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First use git remote update  to bring your remote refs up to date  Then you can do one of several things  such as    git status -uno will tell you whether the branch you are tracking is ahead  behind or has diverged  If it says nothing  the local and remote are the same  git show-branch  master will show you the commits in all of the branches whose names end in  master   eg master and origin master     If you use -v with git remote update  git remote -v update  you can see which branches got updated  so you don t really need any further commands   However  it looks like you want to do this in a script or program and end up with a true false value  If so  there are ways to check the relationship between your current HEAD commit and the head of the branch you re tracking  although since there are four possible outcomes you can t reduce it to a yes no answer  However  if you re prepared to do a pull --rebase then you can treat  local is behind  and  local has diverged  as  need to pull   and the other two as  don t need to pull    You can get the commit id of any ref using git rev-parse  lt ref gt   so you can do this for master and origin master and compare them  If they re equal  the branches are the same  If they re unequal  you want to know which is ahead of the other  Using git merge-base master origin master will tell you the common ancestor of both branches  and if they haven t diverged this will be the same as one or the other  If you get three different ids  the branches have diverged   To do this properly  eg in a script  you need to be able to refer to the current branch  and the remote branch it s tracking  The bash prompt-setting function in  etc bash completion d has some useful code for getting branch names  However  you probably don t actually need to get the names  Git has some neat shorthands for referring to branches and commits  as documented in git rev-parse --help   In particular  you can use   for the current branch  assuming you re not in a detached-head state  and   u  for its upstream branch  eg origin master   So git merge-base     u  will return the  hash of the  commit at which the current branch and its upstream diverge and git rev-parse   and git rev-parse   u  will give you the hashes of the two tips  This can be summarized in the following script      bin sh  UPSTREAM   1 -   u    LOCAL   git rev-parse    REMOTE   git rev-parse   UPSTREAM   BASE   git merge-base     UPSTREAM    if    LOCAL    REMOTE    then     echo  Up-to-date  elif    LOCAL    BASE    then     echo  Need to pull  elif    REMOTE    BASE    then     echo  Need to push  else     echo  Diverged  fi   Note  older versions of git didn t allow   on its own  so you may have to use   0  instead   The line UPSTREAM   1 -   u    allows you optionally to pass an upstream branch explicitly  in case you want to check against a different remote branch than the one configured for the current branch  This would typically be of the form remotename branchname  If no parameter is given  the value defaults to   u    The script assumes that you ve done a git fetch or git remote update first  to bring the tracking branches up to date  I didn t build this into the script because it s more flexible to be able to do the fetching and the comparing as separate operations  for example if you want to compare without fetching because you already fetched recently

User · Answer

For the windows users who end up on this question looking for this  I ve modified some of the answer into a powershell script  Tweak as necessary  save to a  ps1 file and run on demand or scheduled if you like   cd C   lt path to repo gt  git remote update                            update remote  msg   git remote show origin                capture status  update    msg -like   local out of date   if  update length -gt 0                      if local needs update     Write-Host   needs update       git pull     git reset --hard origin master     Write-Host   local updated     else       Write-Host   no update needed

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Because Neils answer helped me so much here is a Python translation with no dependencies   import os import logging import subprocess  def check for updates directory str  - gt  None         Check git repo state in respect to remote        git cmd   lambda cmd  subprocess run            git     cmd          cwd directory          stdout subprocess PIPE          check True          universal newlines True  stdout rstrip   n        origin   git cmd   config    --get    remote origin url        logging debug  Git repo origin   r   origin      for line in git cmd   fetch             logging debug line      local sha   git cmd   rev-parse             remote sha   git cmd   rev-parse      u         base sha   git cmd   merge-base           u         if local sha    remote sha          logging info  Repo is up to date       elif local sha    base sha          logging info  You need to pull       elif remote sha    base sha          logging info  You need to push       else          logging info  Diverged    check for updates os path dirname   file       hth

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I suggest you go see the script https   github com badele gitcheck  I have coded this script for check in one pass all your Git repositories  and it shows who has not committed and who has not pushed pulled   Here a sample result

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There are many very feature rich and ingenious answers already  To provide some contrast  I could make do with a very simple line     Check return value to see if there are incoming updates  if   git diff --quiet remotes origin HEAD  then    pull or whatever you want to do fi

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The command  git ls-remote origin -h refs heads master   will list the current head on the remote -- you can compare it to a previous value or see if you have the SHA in your local repo

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I based this solution on the comments of  jberger   if git checkout master  amp  amp      git fetch origin master  amp  amp         git rev-list HEAD   origin master --count     0    amp  amp      git merge origin master then     echo  Updated   else     echo  Not updated   fi

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This one-liner works for me in zsh  from  Stephen Haberman s answer  git fetch      git rev-parse HEAD      git rev-parse   u            amp  amp  echo  quot Up to date quot     echo  quot Not up to date quot

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I think the best way to do this would be   git diff remotes origin HEAD   Assuming that you have the this refspec registered  You should if you have cloned the repository  otherwise  i e   if the repo was created de novo locally  and pushed to the remote   you need to add the refspec explicitly

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The below script works perfectly   changed 0 git remote update  amp  amp  git status -uno   grep -q  Your branch is behind   amp  amp  changed 1 if    changed   1    then     git pull     echo  Updated successfully   else     echo  Up-to-date  fi

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Using simple regexp   str   git status   if     str      Your  branch  is  behind  by  commits   and  can  be  fast-forwarded     then     echo  date    Y- m- d  H  M  S    Needs pull  else     echo  Code is up to date  fi

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Here s my version of a Bash script that checks all repositories in a predefined folder   https   gist github com henryiii 5841984  It can differentiate between common situations  like pull needed and push needed  and it is multithreaded  so the fetch happens all at once  It has several commands  like pull and status   Put a symlink  or the script  in a folder in your path  then it works as git all status    etc    It only supports origin master  but it can be edited or combined with another method

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Run git fetch  remote  to update your remote refs  it ll show you what s new  Then  when you checkout your local branch  it will show you whether it s behind upstream

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After reading many answers and multiple posts  and spending half a day trying various permutations  this is what I have come up with   If you are on Windows  you may run this script in Windows using Git Bash provided by Git for Windows  installation or portable    This script requires arguments   - local path e g   d source project1 - Git URL e g  https   username bitbucket org username project1 git - password  if a password should not be entered on the command line in plain text  then modify the script to check if GITPASS is empty  do not replace and let Git prompt for a password   The script will  - Find the current branch - Get the SHA1 of the remote on that branch - Get the SHA1 of the local on that branch - Compare them    If there is a change as printed by the script  then you may proceed to fetch or pull  The script may not be efficient  but it gets the job done for me   Update - 2015-10-30  stderr to dev null to prevent printing the URL with the password to the console      bin bash    Shell script to check if a Git pull is required   LOCALPATH  1 GITURL  2 GITPASS  3  cd  LOCALPATH BRANCH    git rev-parse --abbrev-ref HEAD    echo echo git url    GITURL echo branch    BRANCH    Bash replace - replace   with  password  in the GIT URL GITURL2    GITURL     GITPASS    FOO    git ls-remote  GITURL2 -h  BRANCH 2 gt   dev null   if            0     then   echo cannot get remote status   exit 2 fi FOO ARRAY   FOO  BAR   FOO ARRAY 0   echo   BAR   LOCALBAR    git rev-parse HEAD   echo   LOCALBAR  echo  if     BAR       LOCALBAR     then    read -t10 -n1 -r -p  Press any key in the next ten seconds     key   echo No changes   exit 0 else    read -t10 -n1 -r -p  Press any key in the next ten seconds     key    echo pressed  key   echo There are changes between local and remote repositories    exit 1 fi

User · Answer

You can also find a Phing script who does that now   I needed a solution to update my production environments automatically and we re very happy thanks to this script that I m sharing   The script is written in XML and needs Phing

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Maybe this  if you want to add task as crontab      bin bash dir   path to root  lock  tmp update lock msglog   var log update log   log             echo    date    1 -missing    gt  gt   msglog    if   -f  lock    then         log  Already run  exiting     else          gt   lock         git -C    dir remote update  amp  gt   dev null         checkgit  git -C    dir status          if        checkgit      Your branch is up-to-date      then                 log  -------------- Update ---------------                  git -C    dir pull  amp  gt  gt   msglog                 log  -------------------------------------          fi         rm  lock  fi exit 0

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I use a version of a script based on Stephen Haberman s answer   if   -n   1     then     gitbin  git -C  1  else     gitbin  git  fi    Fetches from all the remotes  although --all can be replaced with origin  gitbin fetch --all if      gitbin rev-parse HEAD        gitbin rev-parse   u      then      gitbin rebase   u  --preserve-merges fi   Assuming this script is called git-fetch-and-rebase  it can be invoked with an optional argument directory name of the local Git repository to perform operation on  If the script is called with no arguments  it assumes the current directory to be part of the Git repository   Examples     Operates on  abc def my-git-repo-dir git-fetch-and-rebase  abc def my-git-repo-dir    Operates on the Git repository which the current working directory is part of git-fetch-and-rebase   It is available here as well

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git ls-remote   cut -f1   git cat-file --batch-check  gt  amp -   will list everything referenced in any remote that isn t in your repo   To catch remote ref changes to things you already had  e g  resets to previous commits  takes a little more   git pack-refs --all mine  mktemp  sed      d      G s         n           1  2       h   git packed-refs   sort -k2  gt  mine for r in  git remote   do      echo Checking  r         git ls-remote  r   sort -k2   diff -b -  mine   grep    lt  done

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All such complex sugestions while the solution is so short and easy      bin bash  BRANCH   lt your branch name gt   LAST UPDATE  git show --no-notes --format format   H   BRANCH   head -n 1  LAST COMMIT  git show --no-notes --format format   H  origin  BRANCH   head -n 1   git remote update if    LAST COMMIT     LAST UPDATE    then         echo  Updating your branch  BRANCH          git pull --no-edit else         echo  No updates available  fi

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Here s a Bash one-liner that compares the current branch s HEAD commit hash against its remote upstream branch  no heavy git fetch or git pull --dry-run operations required       git rev-parse HEAD      git ls-remote   git rev-parse --abbrev-ref   u      sed  s      g     cut -f1     amp  amp  echo up to date    echo not up to date   Here s how this somewhat dense line is broken down    Commands are grouped and nested using   x  Bash command-substitution syntax  git rev-parse --abbrev-ref   u  returns an abbreviated upstream ref  e g  origin master   which is then converted into space-separated fields by the piped sed command  e g  origin master  This string is fed into git ls-remote which returns the head commit of the remote branch  This command will communicate with the remote repository  The piped cut command extracts just the first field  the commit hash   removing the tab-separated reference string  git rev-parse HEAD returns the local commit hash  The Bash syntax   a   b    amp  amp  x    y completes the one-liner  this is a Bash string-comparison   within a test construct   test    followed by and-list and or-list constructs  amp  amp  true    false

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I just want to post this as an actual post as it is easy to miss this in the comments   The correct and best answer for this question was given by  Jake Berger  Thank you very much dude  everyone need this and everyone misses this in the comments  So for everyone struggling with this here is the correct answer  just use the output of this command to know if you need to do a git pull  if the output is 0 then obviously there is nothing to update    stackoverflow  give this guy a bells  Thanks   Jake Berger  git rev-list HEAD   origin master --count will give you the total number of  different  commits between the two      Jake Berger Feb 5  13 at 19 23

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If you have an upstream branch  git fetch  lt remote gt  git status   If you don t have an upstream branch  Compare the two branches   git fetch  lt remote gt  git log  lt local branch name gt    lt remote branch name gt  --oneline   For example   git fetch origin    See if there are any incoming changes git log HEAD  origin master --oneline    I m assuming origin master is your remote tracking branch   If any commits are listed in the output above  then you have incoming changes -- you need to merge   If no commits are listed by git log then there is nothing to merge   Note that this will work even if you are on a feature branch -- that does not have a tracking remote  since if explicitly refers to origin master instead of implicitly using the upstream branch remembered by Git

[git] Check if pull needed in Git

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