Git - how to find first commit of specific branch

In following example tree:

A-B-C-D-E (master branch)
    \
     F-G-H (xxx branch)

I'm looking for F - the first commit in xxx branch. I think that it is possible with:

git log xxx --not master

and the last listed commit should be F. Is it correct solution or maybe there are some disadvantages of it?

I know that there were similar questions on stackoverflow, but nobody proposed such solution, and I'm not sure if I do it right.

git log master..branch --oneline | tail -1

Where "branch" is your specific branch name. The dot-dot gives you all of the commits that the branch has that master doesn't have. tail -1 returns the last line from the previous output.

You should use the merge-base functionality which is designed to solve exactly this:

git merge-base remotes/origin/<branch> develop 

git cherry master -v | head -n 1

cherry - Shows the commits on your current branch that aren't present on a branch upstream (docs). An upstream (master in this case) is a point your current branch derives from.

-v - Shows commit names (instead of just SHA's) - verbose.

head - Unix command which prints n number of lines from a text

If your branch (old one) once again merged back to master doesn't give expected result.I have using python script to find initial branch commit Id.

git rev-list --first-parent changeset

--first-parent follow only the first parent commit upon seeing a merge commit.

Iterate changeset's from above command until parent branch found.

def status_check(exec_command, exec_dir=None, background=False):
    if exec_dir:
        os.chdir(exec_dir)
    res = subprocess.Popen(exec_command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    if not background:
        result = res.communicate()
    return result



def findNewBranchCommits(changeset=None):
	cmd = "git rev-list --first-parent "+ changeset
	rev_list = status_check(cmd,self.module_dir)
	rev_list = str(rev_list[0]).split('\n')
	rev_list = list(filter(None, rev_list))
	for x in rev_list:	 					# Iterate until branch base point
		rev_cmd = "git branch --contains " + x
		rev_cmd = status_check(rev_cmd,self.module_dir)
		rev_cmd = str(rev_cmd[0]).split('\n')
		if(len(rev_cmd) > 2): 
			print "First Commit in xxx branch",x
			break

findNewBranchCommits(changeset)

git cherry master -v | tail -1   

however this will only give you the first commit on branch xxx that is not in master, not the first commit on branch xxx ever. the latter would be difficult if branch xxx has been deleted and/or re-created one or more times. it that case you could try the following:

git reflog | grep checkout | grep xxx | tail -1   

git rev-list --ancestry-path $(git merge-base master xxx)..xxx | tail -1

I tried this command and it worked:

git log <source_branch> <feature_branch> --oneline | tail -1