blocks|key|2744515|text|它应该会给你类似这样的东西：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2744516|$+git+log+cee157
error:+short+SHA1+cee157+is+ambiguous.
error:+short+SHA1+cee157+is+ambiguous.
fatal:+ambiguous+argument+'cee157':+unknown+revision+or+path+not+in+the+working+tree.
Use+'--'+to+separate+paths+from+revisions,+like+this:
'git+<command>+[<revision>...]+--+[<file>...]'|code-block|syntax|javascript|2744517|我刚刚在一个真实的Git存储库上进行了测试，通过查找带有重复前缀的提交，如下所示：|2744518|git+rev-list+master+%7C+cut+-c-4+%7C+sort+%7C+uniq+-c+%7C+sort+-nr+%7C+head|2744519|这将获取master中的修订列表，去掉前4个字符，丢弃其余的，计算重复项并按数字排序。在我的一个大约1500次提交的相对较小的存储库中，我发现了相当多的带有常见4位前缀的修订。我选择了4位数的前缀，因为这似乎是Git支持的最短的合法长度。(不适用于3位或更少的数字，即使不是模棱两可。)|offset|length|style|CODE|2744520|顺便说一句，这不是一个拼写错误，我不知道为什么关于歧义SHA1的错误消息会出现两次，而不管重复的SHA1的数量(尝试使用2和3)：|2744521|error:+short+SHA1+cee157+is+ambiguous.
error:+short+SHA1+cee157+is+ambiguous.|2744522|(都在stderr上。实际上，整个输出都在stderr上，而不是在stdout上。)|2744523|在Windows中测试：|2744524|$+git+--version
git+version+1.8.1.msysgit.1|2744525|我认为可以肯定地说，如果你的版本是Git1.8.1，>=会警告你有重复的地方。(它将拒绝使用重复项进行操作。)我猜更老的版本也是这样的。|2744526|更新|BOLD|2744527|在测试时，由于environment.c中的int+minimum_abbrev+=+4，您至少需要4位数的SHA1。(感谢@devnull指出这一点！)|2744528|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/git/git/blob/master/environment.c|1|https://stackoverflow.com/users/2235132/devnull^0|0|0|0|0|4|6|0|0|0|3|6|L|6|X|6|0|0|0|0|0|2|0|M|M|7|D|0|1Q|8|1|0^^$0|@$1|2|3|4|5|6|7|1H|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1I|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1J|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|1K|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|1L|8|@$M|1M|N|1N|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1O|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|1P|8|@]|9|@]|A|$E|F]]|$1|U|3|V|5|6|7|1Q|8|@$M|1R|N|1S|O|P]|$M|1T|N|1U|O|P]|$M|1V|N|1W|O|P]]|9|@]|A|$]]|$1|W|3|X|5|6|7|1X|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1Y|8|@]|9|@]|A|$E|F]]|$1|10|3|11|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|12|3|13|5|6|7|20|8|@$M|21|N|22|O|14]]|9|@]|A|$]]|$1|15|3|16|5|6|7|23|8|@$M|24|N|25|O|P]]|9|@$M|26|N|27|1|28]|$M|29|N|2A|1|2B]]|A|$]]|$1|17|3|-4|5|6|7|2C|8|@]|9|@]|A|$]]]|18|$19|$5|1A|1B|1C|A|$1D|1E]]|1F|$5|1A|1B|1C|A|$1D|1G]]]]

It should give you something like this:

<pre><code>$ git log cee157
error: short SHA1 cee157 is ambiguous.
error: short SHA1 cee157 is ambiguous.
fatal: ambiguous argument 'cee157': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git &lt;command&gt; [&lt;revision&gt;...] -- [&lt;file&gt;...]'
</code></pre>

I just tested this on a real Git repository, by finding commits with duplicate prefixes like this:

<pre><code>git rev-list master | cut -c-4 | sort | uniq -c | sort -nr | head
</code></pre>

This takes the list of revisions in <code>master</code>, cuts out the first 4 characters and throws away the rest, count the duplicates and sort numerically. In a my relatively small repository of ~1500 commits I found quite a few revisions with a common 4-digit prefix. I chose a 4-digit prefix because that seems to be the shortest legal length supported by Git. (Doesn't work with 3 digits or less, even if not ambiguous.)

Btw this was not a typo, I don't know why the error message about ambiguous SHA1 appears twice, regardless of the number of duplicate SHA1 (tried with 2 and 3):

<pre><code>error: short SHA1 cee157 is ambiguous.
error: short SHA1 cee157 is ambiguous.
</code></pre>

(Both on <code>stderr</code>. Actually the entire output is on <code>stderr</code>, nothing on <code>stdout</code>.)

Tested in Windows:

<pre><code>$ git --version
git version 1.8.1.msysgit.1
</code></pre>

I think it's safe to say that if your version is >= 1.8.1, Git will warn you of duplicates. (It will refuse to operate with duplicates.) I would guess that much older versions worked this way too.

UPDATE

When testing this, you need a minimum of 4-digit SHA1, because of <code>int minimum_abbrev = 4</code> in <a href="https://github.com/git/git/blob/master/environment.c" rel="nofollow noreferrer">environment.c</a>. (Thanks <a href="https://stackoverflow.com/users/2235132/devnull">@devnull</a> for pointing that out!)

blocks|key|155120|text|最初的海报上写着：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|155121|155122|我认为它应该，尽管我找不到任何权威来源说它会。|blockquote|155123|155124|155125|可以在源代码+get_short_sha1()中找到权威来源。|offset|length|style|BOLD|CODE|155126|引用this|155127|if+(!quietly+&&+(status+==+SHORT_NAME_AMBIGUOUS))
++++return+error("short+SHA1+%25.*s+is+ambiguous.",+len,+hex_pfx);|code-block|syntax|javascript|155128|和this|155129|if+(!ds->candidate_checked)
++++/*
+++++*+If+this+is+the+only+candidate,+there+is+no+point
+++++*+calling+the+disambiguation+hint+callback.
+++++*
+++++*+On+the+other+hand,+if+the+current+candidate
+++++*+replaced+an+earlier+candidate+that+did+_not_+pass
+++++*+the+disambiguation+hint+callback,+then+we+do+have
+++++*+more+than+one+objects+that+match+the+short+name
+++++*+given,+so+we+should+make+sure+this+one+matches;
+++++*+otherwise,+if+we+discovered+this+one+and+the+one
+++++*+that+we+previously+discarded+in+the+reverse+order,
+++++*+we+would+end+up+showing+different+results+in+the
+++++*+same+repository!
+++++*/
++++ds->candidate_ok+=+(!ds->disambiguate_fn_used+%7C%7C
++++++++++++++++++++++++ds->fn(ds->candidate,+ds->cb_data));

if+(!ds->candidate_ok)
++++return+SHORT_NAME_AMBIGUOUS;|155130|此外，还存在tests来确保该功能按预期工作。|155131|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/git/git/blob/master/sha1_name.c|1|https://github.com/git/git/blob/master/sha1_name.c#L341|2|https://github.com/git/git/blob/master/sha1_name.c#L201|3|https://github.com/git/git/blob/master/t/t1512-rev-parse-disambiguation.sh^0|0|0|0|0|0|0|6|7|G|7|G|0|0|2|4|1|0|0|1|4|2|0|0|6|5|3|0^^$0|@$1|2|3|4|5|6|7|1F|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1H|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]|$1|G|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|1K|8|@$J|1L|K|1M|L|M]|$J|1N|K|1O|L|N]]|9|@$J|1P|K|1Q|1|1R]]|A|$]]|$1|O|3|P|5|6|7|1S|8|@]|9|@$J|1T|K|1U|1|1V]]|A|$]]|$1|Q|3|R|5|S|7|1W|8|@]|9|@]|A|$T|U]]|$1|V|3|W|5|6|7|1X|8|@]|9|@$J|1Y|K|1Z|1|20]]|A|$]]|$1|X|3|Y|5|S|7|21|8|@]|9|@]|A|$T|U]]|$1|Z|3|10|5|6|7|22|8|@]|9|@$J|23|K|24|1|25]]|A|$]]|$1|11|3|-4|5|6|7|26|8|@]|9|@]|A|$]]]|12|$13|$5|14|15|16|A|$17|18]]|19|$5|14|15|16|A|$17|1A]]|1B|$5|14|15|16|A|$17|1C]]|1D|$5|14|15|16|A|$17|1E]]]]

The original poster states:

<blockquote>
 I think it should, although I can't find any authoritative source that
 says it would.
</blockquote>

The authoritative source can be found in the source code, <a href="https://github.com/git/git/blob/master/sha1_name.c"><code>get_short_sha1()</code></a>. 

Quoting <a href="https://github.com/git/git/blob/master/sha1_name.c#L341">this</a>:

<pre class="lang-c prettyprint-override"><code>if (!quietly &amp;&amp; (status == SHORT_NAME_AMBIGUOUS))
 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
</code></pre>

and <a href="https://github.com/git/git/blob/master/sha1_name.c#L201">this</a>:

<pre class="lang-c prettyprint-override"><code>if (!ds-&gt;candidate_checked)
 /*
 * If this is the only candidate, there is no point
 * calling the disambiguation hint callback.
 *
 * On the other hand, if the current candidate
 * replaced an earlier candidate that did _not_ pass
 * the disambiguation hint callback, then we do have
 * more than one objects that match the short name
 * given, so we should make sure this one matches;
 * otherwise, if we discovered this one and the one
 * that we previously discarded in the reverse order,
 * we would end up showing different results in the
 * same repository!
 */
 ds-&gt;candidate_ok = (!ds-&gt;disambiguate_fn_used ||
 ds-&gt;fn(ds-&gt;candidate, ds-&gt;cb_data));

if (!ds-&gt;candidate_ok)
 return SHORT_NAME_AMBIGUOUS;
</code></pre>

Moreover, <a href="https://github.com/git/git/blob/master/t/t1512-rev-parse-disambiguation.sh">tests</a> also exist to ensure that the feature works as expected.

If <code>cee157</code> can refer to 2 different commit IDs, such as 

<code>cee157eb799af829a9a0c42c0915f55cd29818d4</code> and <code>cee1577fecf6fc5369a80bd6e926ac5f864a754b</code>

will Git warn me if I type in <code>git log cee157</code>? (or Git 1.8.5.2 (Apple Git-48) allows me to type in <code>git log cee1</code>).

I think it should, although I can't find any authoritative source that says it would.

Does Git warn me if a shorthand commit ID can refer to 2 different commits?

Windows

如果cee157可以引用两个不同的提交If，例如cee157eb799af829a9a0c42c0915f55cd29818d4和cee1577fecf6fc5369a80bd6e926ac5f864a754b如果我输入git log cee157，Git会警告我吗？(或者Git 1.8.5.2 (Apple Git-...

问如果一个速记提交ID可以引用两个不同的提交，Git会警告我吗？
EN

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问如果一个速记提交ID可以引用两个不同的提交，Git会警告我吗？EN

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问如果一个速记提交ID可以引用两个不同的提交，Git会警告我吗？
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