blocks|key|1022411|text|这只是一个惯例，即0退出代码表示成功。在几乎所有现代系统上，EXIT_SUCCESS都将为0。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1022412|编辑：|1022413|“为什么test+0和test+1都返回0(成功)+?”|1022414|这是一个完全不同的问题。答案是，将单个参数传递给test总是会成功，除非该参数是空字符串("")。请参阅Open+Group+documentation。|1022415|entityMap|0|LINK|mutability|MUTABLE|url|http://www.cplusplus.com/reference/clibrary/cstdlib/EXIT_SUCCESS/|1|https://www.opengroup.org/onlinepubs/009695399/utilities/test.html^0|U|C|0|0|0|0|1G|O|1|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|D|3|E|5|6|7|X|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|Y|8|@]|9|@]|C|$]]|$1|H|3|I|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|J|3|-4|5|6|7|13|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]|R|$5|M|N|O|C|$P|S]]]]

It's just a convention that a 0 exit code means success. <a href="http://www.cplusplus.com/reference/clibrary/cstdlib/EXIT_SUCCESS/" rel="noreferrer">EXIT_SUCCESS</a> will be 0 on almost every modern system.

EDIT:

"why both test 0 and test 1 returns 0(success) ?"

That's a completely different question. The answer is that passing a single argument to test always results in success unless that argument is the null string (""). See the <a href="https://www.opengroup.org/onlinepubs/009695399/utilities/test.html" rel="noreferrer">Open Group documentation</a>.

blocks|key|1022439|text|通常，程序返回0表示成功，返回非0表示失败；false返回1，因为它是一个方便的非零值，但通常任何非零值都表示某种类型的失败，并且许多程序将返回不同的非零值来指示不同的失败模式|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1022440|entityMap^0|M|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Typically programs return zero for success, non-zero for failure; <code>false</code> returns 1 because it's a convenient non-zero value, but generally any non-zero value means failure of some sort, and many programs will return different non-zero values to indicate different failure modes

blocks|key|1022468|text|这是一个约定，但当你仔细考虑时，它是一个特别有用的约定。一般来说，如果一个程序成功了，你只需要知道这一点。然而，如果它失败了，你可能需要知道关于失败的所有信息-为什么会发生，如何修复它，等等。拥有零意味着‘成功’和非零意味着失败让你可以很容易地检查成功，并调查特定的错误以获得更多细节。许多API和框架都有类似的约定-成功返回0的函数和失败的函数返回一个描述特定失败情况的错误代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1022469|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

It's a convention, but a particularly useful one when you think about it. In general, if a program succeeds that's all you need to know. If it fails, however, you might need to know all kinds of information about the failure - why it happened, how to fix it, etc. Having zero mean 'success' and non-zero mean failure lets you can check pretty easily for success, and investigate the particular error for more details if you want to. A lot of APIs and frameworks have a similar convention - functions that succeed return 0 and and those that fail give back an error code describing the particular failure case.

blocks|key|1022527|text|Bash是一种编程(脚本)语言，但它也是一种shell和用户界面。如果0是错误的，那么程序只能显示一种错误。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1022528|然而，在Bash中，任何非零值都是错误的，我们可以使用1-255之间的任何数字来表示错误。这意味着我们可以有许多不同类型的错误。1是一个一般性错误，126表示文件无法执行，127表示“找不到命令”，等等。下面是一些最常见的退出代码的Exit+Codes+With+Special+Meanings列表。|1022529|成功的种类也很多(退出状态为0)。但是，如果成功，将允许您继续下一步-您可以将结果打印到屏幕上，或执行命令等。|1022530|entityMap|0|LINK|mutability|MUTABLE|url|http://tldp.org/LDP/abs/html/exitcodes.html#EXITCODESREF^0|Z|1|0|1S|1|22|3|2E|3|38|W|0|0|E|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|H|3|I|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

Bash is a programming (scripting) language, but it's also a shell and a user-interface. If <code>0</code> was error, then the program could only present one kind of error.

However in Bash, any nonzero value is an error, and we may use any number from 1-255 to represent an error. This means we can have many different kinds of errors. <code>1</code> is a general error, <code>126</code> means that a file cannot be executed, <code>127</code> means 'command not found', etc. Here's a list of Bash <a href="http://tldp.org/LDP/abs/html/exitcodes.html#EXITCODESREF" rel="noreferrer">Exit Codes With Special Meanings</a> showing some of the most common exit codes.

There are also many kinds of success (exit status is <code>0</code>). However, a success will allow you to proceed to the next step&mdash;you can like print results to a screen, or execute a command, etc.

blocks|key|1237227|text|AFAIK这来自C语言的约定，如果成功，你应该返回0。请参见：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1237228|man+close|code-block|syntax|javascript|1237229|大多数C+(POSIX)+api都是这样构建的。http://en.wikipedia.org/wiki/C_POSIX_library|offset|length|1237230|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/C_POSIX_library^0|0|0|O|18|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

AFAIK this come from the C convention that you should return 0 if succeded.
See:

<pre><code>man close
</code></pre>

Most of the C (POSIX) api is build like this.
<a href="http://en.wikipedia.org/wiki/C_POSIX_library" rel="noreferrer">http://en.wikipedia.org/wiki/C_POSIX_library</a>

blocks|key|1237337|text|我发现需要理解的一个基本点是。在bash和unix+shell中，返回值通常不是布尔值。它们是整数退出代码。因此，您必须根据约定对它们进行评估，即0表示成功，其他值表示某些错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1237338|对于test、[+]或[[+]]操作符，如果退出代码为0(/bin/+true的结果)，则bash条件的计算结果为true。否则，它们的计算结果为false。|offset|length|style|CODE|1237339|字符串的计算方式与退出代码不同：|1237340|if+[+0+]+;+then+echo+not+null+;+fi
if+[+$(echo+0)+]+;+then+echo+not+null+;+fi

if+[+-z+""+]+;+then+echo+null+;+fi|code-block|syntax|javascript|1237341|((+))算术运算符将1和0解释为true和false。但该运算符不能完全替代test、[+]或[[+]]。下面是一个显示算术运算符何时有用的示例：|1237342|for+((+counter+=+0+;+counter+<+10+;+counter+%2B%2B+))+;+do
++if+((+counter+%25+2+))+;+then+echo+"odd+number+$counter"+;+fi
done|1237343|entityMap^0|0|2|4|7|3|B|5|0|0|0|0|5|13|4|18|3|1C|5|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]|$D|Y|E|Z|F|G]|$D|10|E|11|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|12|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|13|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|14|8|@$D|15|E|16|F|G]|$D|17|E|18|F|G]|$D|19|E|1A|F|G]|$D|1B|E|1C|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|L|7|1D|8|@]|9|@]|A|$M|N]]|$1|S|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|T|$]]

The one fundamental point I find important to understand is this. In bash and in unix shells in general, return values are not boolean. They are integer exit codes. As such, you must evaluate them according to the convention saying 0 means success, and other values mean some error.

With <code>test</code>, <code>[ ]</code> or <code>[[ ]]</code> operators, bash conditions evaluate as true in case of an exit code of 0 (the result of /bin/true). Otherwise they evaluate as false.

Strings are evaluated differently than exit codes:

<pre><code>if [ 0 ] ; then echo not null ; fi
if [ $(echo 0) ] ; then echo not null ; fi

if [ -z "" ] ; then echo null ; fi
</code></pre>

The <code>(( ))</code> arithmetic operator interprets 1 and 0 as true and false. But that operator cannot be used as a complete replacement for <code>test</code>, <code>[ ]</code> or <code>[[ ]]</code>. Here is an example showing when the arithmetic operator is useful:

<pre><code>for (( counter = 0 ; counter &lt; 10 ; counter ++ )) ; do
 if (( counter % 2 )) ; then echo "odd number $counter" ; fi
done
</code></pre>

blocks|key|1237391|text|你试图将正确/错误等同于成功/失败。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1237392|他们是两个完全不同的人，尽管一开始是微妙的不同！|1237393|在shell脚本中，没有true/false这样的东西。Shell‘expression’不会解释为true/false。相反，shell‘expression’是成功或失败的进程。|1237394|显然，一个过程可能会因为很多原因而失败。因此，我们需要一个更大的集合代码来映射可能的故障。正整数做到了这一点。另一方面，如果该过程成功，这意味着它恰好做了它应该做的事情。因为只有一种方法可以做到这一点，所以我们只需要一个代码。0可以解决这个问题。|1237395|在C语言中，我们正在创建一个程序。在shell脚本中，我们运行一系列的程序来完成一些事情。|1237396|不同！|1237397|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|P|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|Q|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|S|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|M|$]]

Your trying to equate true/false with success/failure. 

They are two completely, although subtly at first, different dichotomies!

In shell scripting, there is no such thing as true/false. Shell 'expressions' aren't interpreted as true/false. Rather, shell 'expressions' are processes that either succeed or fail.

Obviously, a process might fail for many reasons. Thus we need a larger set codes to map possible failures to. The positive integers do the trick. On the other hand, if the process succeeds, that means it did exactly what it was supposed to do. Since there is only one way to do that, we only need one code. 0 does the trick.

In C, we are creating a program. In a shell script, we are running a bunch of programs to get something done.

Difference!

blocks|key|1237456|text|这是一个可以追溯到Unix早期的约定。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1237457|按照惯例，如果成功，则所有系统调用都返回0，否则返回非零值，因为可以使用不同的数字来指示失败的不同原因。|1237458|Shell遵循此约定，0表示最后一个命令成功，否则为非零。类似地，非零返回值对于输出错误消息也很方便:例如，1：“脑死亡”，2：“冷酷无情”，等等。|1237459|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

it's a convention dated back to the early days of Unix.

By convention, all system calls return 0 if succeed, non-zero otherwise, because then different numbers can be used to indicate different reason of failure.

Shells follow this convention, 0 means last command succeeded, non-zero otherwise. Similarly, the non-zero return value comes in handy for output error messages: e.g. 1: "brain dead", 2: "heartless", and so on.

blocks|key|1022826|text|虽然这个问题不是针对C编程的，而且大多数答案似乎间接地解释了真正的原因，但我想我会回答，我希望C程序员会发现有用的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1022827|IMHO，歧义的真正来源是C标准。例如，在C11草案规范(http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf)的"7.22.4.4+the+exit+function“与"7.18+Boolean+type+and+values+”一节中，EXIT_SUCCESS是零，这是从linux+shell命令行运行的程序在成功时期望返回的值，而bool+true是非零(#define‘’ed为1，但称其为非零更安全。为什么会这样呢？请参阅https://stackoverflow.com/users/827263/keith-thompson在https://stackoverflow.com/a/40009047/4726668中的评论)。|offset|length|1022828|引用C11草案规范(http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf)：|1022829|7.22.4.4+exit函数|1022830|“|1022831|5最后，控制权返回到主机环境。如果status的值为0或EXIT_SUCCESS，则返回成功销毁状态的实现定义形式。如果status的值为EXIT_FAILURE，则返回未成功销毁状态的实现定义形式。否则，返回的状态是实现定义的。|1022832|1022833|vs|1022834|7.18布尔类型和值|1022835|1022836|3剩下的三个宏适用于#if预处理指令。他们是|1022837|真的|1022838|其扩展为整数常数1，|1022839|错误|1022840|它扩展为整数常量0，并且|1022841|_+_bool_true_false_are_defined|1022842|其扩展为整数常量1。|1022843|1022844|entityMap|0|LINK|mutability|MUTABLE|url|http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf|1|https://stackoverflow.com/users/827263/keith-thompson|2|https://stackoverflow.com/a/40009047/4726668|3^0|0|T|1L|0|6X|1H|1|8F|18|2|0|A|1L|3|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1M|8|@]|9|@$D|1N|E|1O|1|1P]|$D|1Q|E|1R|1|1S]|$D|1T|E|1U|1|1V]]|A|$]]|$1|F|3|G|5|6|7|1W|8|@]|9|@$D|1X|E|1Y|1|1Z]]|A|$]]|$1|H|3|I|5|6|7|20|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|21|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|22|8|@]|9|@]|A|$]]|$1|N|3|K|5|6|7|23|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|24|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|25|8|@]|9|@]|A|$]]|$1|S|3|K|5|6|7|26|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|27|8|@]|9|@]|A|$]]|$1|V|3|W|5|6|7|28|8|@]|9|@]|A|$]]|$1|X|3|Y|5|6|7|29|8|@]|9|@]|A|$]]|$1|Z|3|10|5|6|7|2A|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|2B|8|@]|9|@]|A|$]]|$1|13|3|14|5|6|7|2C|8|@]|9|@]|A|$]]|$1|15|3|16|5|6|7|2D|8|@]|9|@]|A|$]]|$1|17|3|K|5|6|7|2E|8|@]|9|@]|A|$]]|$1|18|3|-4|5|6|7|2F|8|@]|9|@]|A|$]]]|19|$1A|$5|1B|1C|1D|A|$1E|1F]]|1G|$5|1B|1C|1D|A|$1E|1H]]|1I|$5|1B|1C|1D|A|$1E|1J]]|1K|$5|1B|1C|1D|A|$1E|1F]]]]

Although the question is not tagged for C programming and most answers seem to explain the real reason indirectly, I thought I'll answer, what I hope, a C programmer would find useful.
IMHO, the true source of ambiguity is the C standard. For example, in C11 draft spec's (<a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf" rel="nofollow noreferrer">http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf</a>) Section &quot;7.22.4.4 The exit function&quot; vs Section &quot;7.18 Boolean type and values &lt;stdbool.h&gt;&quot;, EXIT_SUCCESS is zero, which is what programs run from the linux shell cmdline are expected to return on success, whereas, bool true is non-zero (#define'ed to 1, but safer to call it non-zero. Why is that? Refer to <a href="https://stackoverflow.com/users/827263/keith-thompson">https://stackoverflow.com/users/827263/keith-thompson</a> 's comment in <a href="https://stackoverflow.com/a/40009047/4726668">https://stackoverflow.com/a/40009047/4726668</a> ).
Quoting from C11 draft spec (<a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf" rel="nofollow noreferrer">http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf</a>):
7.22.4.4 The exit function
&quot;
5 Finally, control is returned to the host environment. If the value of status is zero or EXIT_SUCCESS, an implementation-defined form of the status successful termination is returned. If the value of status is EXIT_FAILURE, an implementation-defined form of the status unsuccessful termination is returned. Otherwise the status returned is implementation-defined.
&quot;
vs
7.18 Boolean type and values &lt;stdbool.h&gt;
&quot;
3
The remaining three macros are suitable for use in #if preprocessing directives. They are
true
which expands to the integer constant 1,
false
which expands to the integer constant 0, and
_ _bool_true_false_are_defined
which expands to the integer constant 1.
&quot;

<pre><code>false; echo $?
</code></pre>

The above will output <code>1</code>, which is contradictory with all other programming languages I know.

Any reason in this?

Why 0 is true but false is 1 in the shell?

false; echo $?上面的代码将输出1，这与我所知道的所有其他编程语言都是矛盾的。这里面有什么原因吗？

问为什么在shell中0是true，而false是1？
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问为什么在shell中0是true，而false是1？
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