blocks|key|1131517|text|还要注意，每个命令的退出状态都存储在外壳变量$中，您可以在运行命令后立即检查该变量。非零状态表示故障：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1131518|my_command
if+[+$?+-eq+0+]
then
++++echo+"it+worked"
else
++++echo+"it+failed"
fi|code-block|syntax|javascript|1131519|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Note also, each command's exit status is stored in the shell variable $?, which you can check immediately after running the command. A non-zero status indicates failure:

<pre><code>my_command
if [ $? -eq 0 ]
then
 echo "it worked"
else
 echo "it failed"
fi
</code></pre>

blocks|key|1131553|text|其他答案已经很好地涵盖了直接问题，但您也可能对使用set+-e感兴趣。这样，任何失败的命令(在特定上下文之外，如if测试)都将导致脚本中止。对于某些脚本，它非常有用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1131554|entityMap^0|P|6|1K|2|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

The other answers have covered the direct question well, but you may also be interested in using <code>set -e</code>. With that, any command that fails (outside of specific contexts like <code>if</code> tests) will cause the script to abort. For certain scripts, it's very useful.

blocks|key|916865|text|我已经破解了下面的成语：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|916866|echo+"Generating+from+IDL..."
idlj+-fclient+-td+java/src+echo.idl
if+[+$?+-ne+0+];+then+{+echo+"Failed,+aborting."+;+exit+1;+}+fi

echo+"Compiling+classes..."
javac+*java
if+[+$?+-ne+0+];+then+{+echo+"Failed,+aborting."+;+exit+1;+}+fi

echo+"Done."|code-block|syntax|javascript|916867|在每个命令前面加上信息回显，然后在每个命令后面加上相同内容|916868|if+[+$?+-ne+0+];...线路。(当然，如果愿意，您可以编辑该错误消息。)|offset|length|style|CODE|916869|entityMap^0|0|0|0|0|J|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@$K|U|L|V|M|N]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I've hacked up the following idiom:

<pre><code>echo "Generating from IDL..."
idlj -fclient -td java/src echo.idl
if [ $? -ne 0 ]; then { echo "Failed, aborting." ; exit 1; } fi

echo "Compiling classes..."
javac *java
if [ $? -ne 0 ]; then { echo "Failed, aborting." ; exit 1; } fi

echo "Done."
</code></pre>

Precede each command with an informative echo, and follow each command with that same 
 <code>if [ $? -ne 0 ];...</code> line. (Of course, you can edit that error message if you want to.)

blocks|key|916922|text|如果您希望脚本中所有命令都具有这种行为，只需添加|type|unstyled|depth|inlineStyleRanges|entityRanges|data|916923|set+-e+
set+-o+pipefail|code-block|syntax|javascript|916924|在脚本的开头。这两个选项告诉bash解释器在命令返回非零退出代码时退出。(有关为什么需要pipefail的更多详细信息，请参阅http://petereisentraut.blogspot.com/2010/11/pipefail.html)|offset|length|style|CODE|916925|但是，这不允许您打印退出消息。|916926|entityMap|0|LINK|mutability|MUTABLE|url|http://petereisentraut.blogspot.com/2010/11/pipefail.html^0|0|0|18|8|1R|1L|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]]|9|@$I|11|J|12|1|13]]|A|$]]|$1|M|3|N|5|6|7|14|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

If you want that behavior for all commands in your script, just add
<pre><code>set -e 
set -o pipefail
</code></pre>
at the beginning of the script. This pair of options tell the bash interpreter to exit whenever a command returns with a non-zero exit code. (For more details about why <code>pipefail</code> is needed, see <a href="http://petereisentraut.blogspot.com/2010/11/pipefail.html" rel="nofollow noreferrer">http://petereisentraut.blogspot.com/2010/11/pipefail.html</a>)
This does not allow you to print an exit message, though.

blocks|key|1131690|text|如果您想保留退出错误状态，也可以使用，并拥有一个每行一个命令的可读文件：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1131691|my_command1+%7C%7C+exit+$?
my_command2+%7C%7C+exit+$?|code-block|syntax|javascript|1131692|但是，这不会打印任何额外的错误消息。但在某些情况下，失败的命令无论如何都会打印出错误。|1131693|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can also use, if you want to preserve exit error status, and have a readable file with one command per line:

<pre><code>my_command1 || exit $?
my_command2 || exit $?
</code></pre>

This, however will not print any additional error message. But in some cases, the error will be printed by the failed command anyway.

blocks|key|1131760|text|trap外壳内置允许捕获信号和其他有用的情况，包括失败的命令执行(即，非零返回状态)。因此，如果您不想显式地测试每个命令的返回状态，那么可以指定为trap+"your+shell+code"+ERR，并且只要命令返回非零状态，就会执行shell代码。例如：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1131761|trap+"echo+script+failed;+exit+1"+ERR|1131762|请注意，与其他捕获失败命令的情况一样，管道需要特殊处理；上面的命令不会捕获false+%7C+true。|1131763|entityMap^0|0|4|21|Q|0|0|11|0|11|C|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|K|$]]

The <code>trap</code> shell builtin allows catching signals, and other useful conditions, including failed command execution (i.e., a non-zero return status). So if you don't want to explicitly test return status of every single command you can say <code>trap "your shell code" ERR</code> and the shell code will be executed any time a command returns a non-zero status. For example:

<code>trap "echo script failed; exit 1" ERR</code> 

Note that as with other cases of catching failed commands, pipelines need special treatment; the above won't catch <code>false | true</code>.

blocks|key|917075|text|直接使用exit可能很棘手，因为脚本可能来自其他地方(例如来自终端)。我更喜欢使用带有set+-e的subshell+(加上错误应该放到cerr中，而不是cout中)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|917076|set+-e
ERRCODE=0
my_command+%7C%7C+ERRCODE=$?
test+$ERRCODE+==+0+%7C%7C
++++(>&2+echo+"My+command+failed+($ERRCODE)";+exit+$ERRCODE)|code-block|syntax|javascript|917077|entityMap^0|4|4|17|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Using <code>exit</code> directly may be tricky as the script may be sourced from other places (e.g. from terminal). I prefer instead using subshell with <code>set -e</code> (plus errors should go into cerr, not cout) :
<pre><code>set -e
ERRCODE=0
my_command || ERRCODE=$?
test $ERRCODE == 0 ||
 (&gt;&amp;2 echo &quot;My command failed ($ERRCODE)&quot;; exit $ERRCODE)
</code></pre>

I am a noob in shell-scripting. I want to print a message and exit my script if a command fails. I've tried:

<pre><code>my_command &amp;&amp; (echo 'my_command failed; exit)
</code></pre>

but it does not work. It keeps executing the instructions following this line in the script. I'm using Ubuntu and bash.

How to exit if a command failed?

解释器

Ubuntu

我是shell脚本方面的新手。如果命令失败，我想打印一条消息并退出我的脚本。我试过了：my_command && (echo 'my_command failed; exit)但它不起作用。它继续执行脚本中这一行后面的指令。我使用的是Ubuntu和bash。

问如果命令失败，如何退出？
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问如果命令失败，如何退出？EN

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问如果命令失败，如何退出？
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