因为尼尔的回答对我帮助很大，这里是一个没有依赖关系的Python翻译:

import os
import logging
import subprocess

def check_for_updates(directory:str) -> 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

运行git fetch (remote)来更新你的远程引用，它会告诉你什么是新的。然后，当您签出本地分支时，它将显示它是否落后于上游。

首先使用git远程更新，使您的远程参考更新到最新。然后你可以做以下几件事中的一件，比如:

Git status -uno将告诉你你正在跟踪的分支是在前面、后面还是已经偏离。如果没有显示，则本地和远程是相同的。 Git show-branch *master会显示所有以master结尾的分支中的提交(例如master和origin/master)。

如果你在git远程更新(git remote -v update)中使用-v，你可以看到哪些分支被更新了，所以你真的不需要任何进一步的命令。

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 ("local is ahead" and "same") as "don't need to pull".

你可以使用git rev-parse <ref>获得任何ref的提交id，所以你可以对master和origin/master这样做并比较它们。如果它们相等，那么分支是相同的。如果它们不相等，你想知道哪个在前面。使用git merge-base master origin/master会告诉你两个分支的共同祖先，如果它们没有分叉，这将是一个或另一个相同的。如果您得到三个不同的id，则分支已经分离。

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

注意:旧版本的git不允许@单独使用，所以你可能不得不使用@{0}代替。

UPSTREAM=${1:-'@{u}'}允许你显式地传递一个上游分支，以防你想检查一个不同于当前分支配置的远程分支。这通常是remotename/branchname的形式。如果不指定参数，默认值为@{u}。

该脚本假设您已经首先进行了git获取或git远程更新，以使跟踪分支更新到最新。我没有把这个构建到脚本中，因为它更灵活，能够将抓取和比较作为单独的操作，例如，如果你想比较而不抓取，因为你最近已经获取了。

我认为最好的方法是:

git diff remotes/origin/HEAD

假设您已经注册了this refspec。如果您已经克隆了存储库，则应该这样做，否则(例如，如果回购是在本地从头创建的，并推到远程)，则需要显式地添加refspec。

下面是一个Bash一行代码，比较了当前分支的HEAD提交哈希和它的远程上游分支，不需要大量的git获取或git拉取——需要干运行操作:

[ $(git rev-parse HEAD) = $(git ls-remote $(git rev-parse --abbrev-ref @{u} | \
sed 's/\// /g') | cut -f1) ] && echo up to date || echo not up to date

以下是这条有点密集的线是如何被分解的:

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 ] && 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 && true || false.

git ls-remote | cut -f1 | git cat-file --batch-check >&-

将列出所有在任何远程引用，不在你的回购。要捕捉你已经拥有的东西的远程引用更改(例如，重置到以前的提交)需要更多一点:

git pack-refs --all
mine=`mktemp`
sed '/^#/d;/^^/{G;s/.\(.*\)\n.* \(.*\)/\1 \2^{}/;};h' .git/packed-refs | sort -k2 >$mine
for r in `git remote`; do 
    echo Checking $r ...
    git ls-remote $r | sort -k2 | diff -b - $mine | grep ^\<
done