blocks|key|1493960|text|如果使用双括号，也可以在case语句之外使用Marcus's+answer+(*+wildcards)：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1493961|string='My+long+string'
if+[[+$string+==+*"My+long"*+]];+then
++echo+"It's+there!"
fi|code-block|syntax|javascript|1493962|请注意，针形字符串中的空格需要放在双引号之间，*通配符应该放在外部。还要注意，使用的是简单的比较运算符(即==)，而不是正则表达式运算符=~。|style|CODE|1493963|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/229585/3755692^0|M|T|0|0|0|N|1|1H|2|1W|2|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@$A|10|B|11|K|L]|$A|12|B|13|K|L]|$A|14|B|15|K|L]]|9|@]|C|$]]|$1|M|3|-4|5|6|7|16|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

You can use <a href="https://stackoverflow.com/a/229585/3755692">Marcus's answer (* wildcards)</a> outside a case statement, too, if you use double brackets:

<pre><code>string='My long string'
if [[ $string == *"My long"* ]]; then
 echo "It's there!"
fi
</code></pre>

Note that spaces in the needle string need to be placed between double quotes, and the <code>*</code> wildcards should be outside. Also note that a simple comparison operator is used (i.e. <code>==</code>), not the regex operator <code>=~</code>.

blocks|key|1494043|text|如果您更喜欢正则表达式方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1494044|string='My+string';

if+[[+$string+=~+"My"+]];+then
+++echo+"It's+there!"
fi|code-block|syntax|javascript|1494045|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|$]]

If you prefer the regex approach:
<pre><code>string='My string';

if [[ $string =~ &quot;My&quot; ]]; then
 echo &quot;It's there!&quot;
fi
</code></pre>

blocks|key|1709028|text|我不确定是否使用if语句，但您可以使用case语句获得类似的效果：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1709029|case+"$string"+in+
++*foo*)
++++#+Do+stuff
++++;;
esac|code-block|syntax|javascript|1709030|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|$]]

I am not sure about using an if statement, but you can get a similar effect with a case statement:

<pre><code>case "$string" in 
 *foo*)
 # Do stuff
 ;;
esac
</code></pre>

blocks|key|1709234|text|您应该记住，shell脚本不是一种语言，而更像是命令的集合。本能地，您会认为这种“语言”要求您在if后面加上[或[[。这两个命令都只是返回指示成功或失败的退出状态的命令(就像其他命令一样)。因此，我使用grep，而不是[命令。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1709235|只需这样做：|1709236|if+grep+-q+foo+<<<"$string";+then
++++echo+"It's+there"
fi|code-block|syntax|javascript|1709237|既然您将if看作是测试它后面的命令的退出状态(以分号结束)，为什么不重新考虑您正在测试的字符串的来源呢？|1709238|##+Instead+of+this
filetype="$(file+-b+"$1")"
if+grep+-q+"tar+archive"+<<<"$filetype";+then
#...

##+Simply+do+this
if+file+-b+"$1"+%7C+grep+-q+"tar+archive";+then
#...|1709239|-q选项使grep不输出任何内容，因为我们只需要返回代码。<<<使shell展开下一个单词，并将其用作命令的输入，该命令是<<+here文档的单行版本(我不确定这是标准的还是巴什主义的)。|1709240|entityMap^0|1C|2|1I|1|1K|2|2T|4|31|1|0|0|0|4|2|0|0|0|2|T|3|1P|2|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|15|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|16|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|T|$]]

You should remember that shell scripting is less of a language and more of a collection of commands. Instinctively you think that this "language" requires you to follow an <code>if</code> with a <code>[</code> or a <code>[[</code>. Both of those are just commands that return an exit status indicating success or failure (just like every other command). For that reason I'd use <code>grep</code>, and not the <code>[</code> command.

Just do:

<pre class="lang-bash prettyprint-override"><code>if grep -q foo &lt;&lt;&lt;"$string"; then
 echo "It's there"
fi
</code></pre>

Now that you are thinking of <code>if</code> as testing the exit status of the command that follows it (complete with semi-colon), why not reconsider the source of the string you are testing?

<pre class="lang-bash prettyprint-override"><code>## Instead of this
filetype="$(file -b "$1")"
if grep -q "tar archive" &lt;&lt;&lt;"$filetype"; then
#...

## Simply do this
if file -b "$1" | grep -q "tar archive"; then
#...
</code></pre>

The <code>-q</code> option makes grep not output anything, as we only want the return code. <code>&lt;&lt;&lt;</code> makes the shell expand the next word and use it as the input to the command, a one-line version of the <code>&lt;&lt;</code> here document (I'm not sure whether this is standard or a Bashism).

blocks|key|1494009|text|公认的答案是最好的，但由于有不止一种方法可以做到这一点，这里有另一个解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1494010|if+[+"$string"+!=+"${string/foo/}"+];+then
++++echo+"It's+there!"
fi|code-block|syntax|javascript|1494011|${var/search/replace}为$var，如果找到search的第一个实例，则将其替换为replace+(它不会更改$var)。如果您尝试不使用任何内容替换foo，并且字符串已更改，则很明显找到了foo。|offset|length|style|CODE|1494012|entityMap^0|0|0|0|L|M|4|V|6|1E|7|1S|4|2C|3|2W|3|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]|$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|N|$]]

The accepted answer is best, but since there's more than one way to do it, here's another solution:

<pre><code>if [ "$string" != "${string/foo/}" ]; then
 echo "It's there!"
fi
</code></pre>

<code>${var/search/replace}</code> is <code>$var</code> with the first instance of <code>search</code> replaced by <code>replace</code>, if it is found (it doesn't change <code>$var</code>). If you try to replace <code>foo</code> by nothing, and the string has changed, then obviously <code>foo</code> was found.

blocks|key|1709348|text|因此，对于这个问题有很多有用的解决方案-但是哪一个最快/使用最少的资源？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1709349|使用此框架进行重复测试：|1709350|/usr/bin/time+bash+-c+'a=two;b=onetwothree;+x=100000;+while+[+$x+-gt+0+];+do+TEST+;+x=$(($x-1));+done'|code-block|syntax|javascript|1709351|每次替换测试：|1709352|[[+$b+=~+$a+]]+++++++++++2.92+user+0.06+system+0:02.99+elapsed+99%25+CPU

[+"${b/$a//}"+=+"$b"+]+++3.16+user+0.07+system+0:03.25+elapsed+99%25+CPU

[[+$b+==+*$a*+]]+++++++++1.85+user+0.04+system+0:01.90+elapsed+99%25+CPU

case+$b+in+*$a):;;esac+++1.80+user+0.02+system+0:01.83+elapsed+99%25+CPU

doContain+$a+$b++++++++++4.27+user+0.11+system+0:04.41+elapsed+99%25CPU|1709353|(doContain在F.+Houri的回答中)|1709354|对于咯咯的笑声：|1709355|echo+$b%7Cgrep+-q+$a+++++++12.68+user+30.86+system+3:42.40+elapsed+19%25+CPU+!ouch!|1709356|因此，无论是在扩展测试中还是在案例中，简单替换选项都可以预测地获胜。这个箱子是便携的。|1709357|输出到100000+greps是可以预见的痛苦！关于无需使用外部实用程序的旧规则仍然有效。|1709358|entityMap^0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|14|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|15|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|16|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|17|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|X|$]]

So there are lots of useful solutions to the question - but which is fastest / uses the fewest resources?

Repeated tests using this frame:

<pre><code>/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do TEST ; x=$(($x-1)); done'
</code></pre>

Replacing TEST each time:

<pre><code>[[ $b =~ $a ]] 2.92 user 0.06 system 0:02.99 elapsed 99% CPU

[ "${b/$a//}" = "$b" ] 3.16 user 0.07 system 0:03.25 elapsed 99% CPU

[[ $b == *$a* ]] 1.85 user 0.04 system 0:01.90 elapsed 99% CPU

case $b in *$a):;;esac 1.80 user 0.02 system 0:01.83 elapsed 99% CPU

doContain $a $b 4.27 user 0.11 system 0:04.41 elapsed 99%CPU
</code></pre>

(doContain was in F. Houri's answer)

And for giggles:

<pre><code>echo $b|grep -q $a 12.68 user 30.86 system 3:42.40 elapsed 19% CPU !ouch!
</code></pre>

So the simple substitution option predictably wins whether in an extended test or a case. The case is portable.

Piping out to 100000 greps is predictably painful! The old rule about using external utilities without need holds true.

blocks|key|1494376|text|Bash+4%2B示例。注意:当单词包含空格等时，不使用引号将导致问题。请始终在Bash，IMO中使用引号。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1494377|下面是一些Bash+4%2B的例子：|1494378|示例1，检查字符串中是否有'yes‘(不区分大小写)：|1494379|++++if+[[+"${str,,}"+==+*"yes"*+]]+;then|code-block|syntax|javascript|1494380|示例2，检查字符串中是否有'yes‘(不区分大小写)：|1494381|++++if+[[+"$(echo+"$str"+%7C+tr+'[:upper:]'+'[:lower:]')"+==+*"yes"*+]]+;then|1494382|示例3，检查字符串中是否有'yes‘(区分大小写)：|1494383|+++++if+[[+"${str}"+==+*"yes"*+]]+;then|1494384|示例4，检查字符串中是否有'yes‘(区分大小写)：|1494385|+++++if+[[+"${str}"+=~+"yes"+]]+;then|1494386|示例5，精确匹配(区分大小写)：|1494387|+++++if+[[+"${str}"+==+"yes"+]]+;then|1494388|示例6，完全匹配(不区分大小写)：|1494389|+++++if+[[+"${str,,}"+==+"yes"+]]+;then|1494390|示例7，精确匹配：|1494391|+++++if+[+"$a"+=+"$b"+]+;then|1494392|示例8，通配符匹配.ext+(不区分大小写)：|1494393|+++++if+echo+"$a"+%7C+egrep+-iq+"\.(mp[3-4]%7Ctxt%7Ccss%7Cjpg%7Cpng)"+;+then|1494394|好好享受吧。|1494395|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1H|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1I|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|1J|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|1K|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|1L|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|1M|8|@]|9|@]|A|$]]|$1|Q|3|R|5|H|7|1N|8|@]|9|@]|A|$I|J]]|$1|S|3|T|5|6|7|1O|8|@]|9|@]|A|$]]|$1|U|3|V|5|H|7|1P|8|@]|9|@]|A|$I|J]]|$1|W|3|X|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|H|7|1R|8|@]|9|@]|A|$I|J]]|$1|10|3|11|5|6|7|1S|8|@]|9|@]|A|$]]|$1|12|3|13|5|H|7|1T|8|@]|9|@]|A|$I|J]]|$1|14|3|15|5|6|7|1U|8|@]|9|@]|A|$]]|$1|16|3|17|5|H|7|1V|8|@]|9|@]|A|$I|J]]|$1|18|3|19|5|6|7|1W|8|@]|9|@]|A|$]]|$1|1A|3|1B|5|H|7|1X|8|@]|9|@]|A|$I|J]]|$1|1C|3|1D|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|1E|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]]|1F|$]]

Bash 4+ examples. Note: not using quotes will cause issues when words contain spaces, etc. Always quote in Bash, IMO.

Here are some examples Bash 4+:

Example 1, check for 'yes' in string (case insensitive):

<pre><code> if [[ "${str,,}" == *"yes"* ]] ;then
</code></pre>

Example 2, check for 'yes' in string (case insensitive):

<pre><code> if [[ "$(echo "$str" | tr '[:upper:]' '[:lower:]')" == *"yes"* ]] ;then
</code></pre>

Example 3, check for 'yes' in string (case sensitive):

<pre><code> if [[ "${str}" == *"yes"* ]] ;then
</code></pre>

Example 4, check for 'yes' in string (case sensitive):

<pre><code> if [[ "${str}" =~ "yes" ]] ;then
</code></pre>

Example 5, exact match (case sensitive):

<pre><code> if [[ "${str}" == "yes" ]] ;then
</code></pre>

Example 6, exact match (case insensitive):

<pre><code> if [[ "${str,,}" == "yes" ]] ;then
</code></pre>

Example 7, exact match:

<pre><code> if [ "$a" = "$b" ] ;then
</code></pre>

Example 8, wildcard match .ext (case insensitive):

<pre><code> if echo "$a" | egrep -iq "\.(mp[3-4]|txt|css|jpg|png)" ; then
</code></pre>

Enjoy.

blocks|key|1494243|text|正如Paul+mentioned在他的性能比较中所说的：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1494244|if+echo+"abcdefg"+%7C+grep+-q+"bcdef";+then
++++echo+"String+contains+is+true."
else
++++echo+"String+contains+is+not+true."
fi|code-block|syntax|javascript|1494245|这与the+answer+provided+by+Marcus中的“case”"$string“一样符合POSIX，但它比case语句answer更容易阅读。还要注意，这将比使用case语句慢得多。正如Paul指出的，不要在循环中使用它。|1494246|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/229551/how-to-check-if-a-string-contains-a-substring-in-bash/25535717#25535717|1|https://stackoverflow.com/questions/229551/how-to-check-if-a-string-contains-a-substring-in-bash/229585#229585^0|2|E|0|0|0|2|T|1|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|K|3|-4|5|6|7|13|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]|S|$5|N|O|P|C|$Q|T]]]]

As <a href="https://stackoverflow.com/questions/229551/how-to-check-if-a-string-contains-a-substring-in-bash/25535717#25535717">Paul mentioned</a> in his performance comparison:

<pre><code>if echo "abcdefg" | grep -q "bcdef"; then
 echo "String contains is true."
else
 echo "String contains is not true."
fi
</code></pre>

This is POSIX compliant like the 'case "$string" in' <a href="https://stackoverflow.com/questions/229551/how-to-check-if-a-string-contains-a-substring-in-bash/229585#229585">the answer provided by Marcus</a>, but it is slightly easier to read than the case statement answer. Also note that this will be much much slower than using a case statement. As Paul pointed out, don't use it in a loop.

blocks|key|1494142|text|这样如何：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1494143|text="+++<tag>bmnmn</tag>++"
if+[[+"$text"+=~+"<tag>"+]];+then
+++echo+"matched"
else
+++echo+"not+matched"
fi|code-block|syntax|javascript|1494144|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|$]]

How about this:

<pre><code>text=" &lt;tag&gt;bmnmn&lt;/tag&gt; "
if [[ "$text" =~ "&lt;tag&gt;" ]]; then
 echo "matched"
else
 echo "not matched"
fi
</code></pre>

blocks|key|1494173|text|This+Stack Overflow+answer是唯一一个捕获空格和破折号字符的工具：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1494174|#+For+null+cmd+arguments+checking+++
to_check='+-t'
space_n_dash_chars='+-'
[[+$to_check+==+*"$space_n_dash_chars"*+]]+&&+echo+found|code-block|syntax|javascript|1494175|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/229606/65706^0|0|Q|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

<a href="https://stackoverflow.com/a/229606/65706">This Stack&nbsp;Overflow answer</a> was the only one to trap space and dash characters:

<pre><code># For null cmd arguments checking 
to_check=' -t'
space_n_dash_chars=' -'
[[ $to_check == *"$space_n_dash_chars"* ]] &amp;&amp; echo found
</code></pre>

blocks|key|1494149|text|一个是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1494150|[+$(expr+$mystring+:+".*${search}.*")+-ne+0+]+&&+echo+'yes'+%7C%7C++echo+'no'|code-block|syntax|javascript|1494151|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|$]]

One is:

<pre><code>[ $(expr $mystring : ".*${search}.*") -ne 0 ] &amp;&amp; echo 'yes' || echo 'no'
</code></pre>

blocks|key|1709394|text|[[+$string+==+*foo*+]]+&&+echo+"It's+there"+%7C%7C+echo+"Couldn't+find"|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1709395|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>[[ $string == *foo* ]] &amp;&amp; echo "It's there" || echo "Couldn't find"
</code></pre>

blocks|key|1709533|text|case+$string+in+(*foo*)
++#+Do+stuff
esac|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1709534|这是与https://stackoverflow.com/a/229585/11267590相同的答案。但是简单的风格和POSIX兼容。|unstyled|offset|length|1709535|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/229585/11267590^0|0|3|17|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre class="lang-sh prettyprint-override"><code>case $string in (*foo*)
 # Do stuff
esac
</code></pre>

This is the same answer as <a href="https://stackoverflow.com/a/229585/11267590">https://stackoverflow.com/a/229585/11267590</a>. But simple style and also POSIX Compliant.

blocks|key|1709418|text|精确的单词匹配：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1709419|string='My+long+string'
exactSearch='long'

if+grep+-E+-q+"\b${exactSearch}\b"+<<<${string}+>/dev/null+2>&1
++then
++++echo+"It's+there"
++fi|code-block|syntax|javascript|1709420|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|$]]

Exact word match:

<pre><code>string='My long string'
exactSearch='long'

if grep -E -q "\b${exactSearch}\b" &lt;&lt;&lt;${string} &gt;/dev/null 2&gt;&amp;1
 then
 echo "It's there"
 fi
</code></pre>

blocks|key|1494312|text|我使用这个函数(没有包含一个依赖项，但很明显)。它通过了下面显示的测试。如果函数返回值大于0，则表示找到了该字符串。您可以很容易地返回1或0。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1494313|function+str_instr+{
+++#+Return+position+of+```str```+within+```string```.
+++#+>>>+str_instr+"str"+"string"
+++#+str:+String+to+search+for.
+++#+string:+String+to+search.
+++typeset+str+string+x
+++#+Behavior+here+is+not+the+same+in+bash+vs+ksh+unless+we+escape+special+characters.
+++str="$(str_escape_special_characters+"${1}")"
+++string="${2}"
+++x="${string%25%25$str*}"
+++if+[[+"${x}"+!=+"${string}"+]];+then
++++++echo+"${#x}+%2B+1"+%7C+bc+-l
+++else
++++++echo+0
+++fi
}

function+test_str_instr+{
+++str_instr+"("+"'foo@host+(dev,web)'"+%7C+assert_eq+11
+++str_instr+")"+"'foo@host+(dev,web)'"+%7C+assert_eq+19
+++str_instr+"["+"'foo@host+[dev,web]'"+%7C+assert_eq+11
+++str_instr+"]"+"'foo@host+[dev,web]'"+%7C+assert_eq+19
+++str_instr+"a"+"abc"+%7C+assert_eq+1
+++str_instr+"z"+"abc"+%7C+assert_eq+0
+++str_instr+"Eggs"+"Green+Eggs+And+Ham"+%7C+assert_eq+7
+++str_instr+"a"+""+%7C+assert_eq+0
+++str_instr+""+""+%7C+assert_eq+0
+++str_instr+"+"+"Green+Eggs"+%7C+assert_eq+6
+++str_instr+"+"+"+Green+"++%7C+assert_eq+1
}|code-block|syntax|javascript|1494314|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|$]]

I use this function (one dependency not included but obvious). It passes the tests shown below. If the function returns a value > 0 then the string was found. You could just as easily return 1 or 0 instead.

<pre><code>function str_instr {
 # Return position of ```str``` within ```string```.
 # &gt;&gt;&gt; str_instr "str" "string"
 # str: String to search for.
 # string: String to search.
 typeset str string x
 # Behavior here is not the same in bash vs ksh unless we escape special characters.
 str="$(str_escape_special_characters "${1}")"
 string="${2}"
 x="${string%%$str*}"
 if [[ "${x}" != "${string}" ]]; then
 echo "${#x} + 1" | bc -l
 else
 echo 0
 fi
}

function test_str_instr {
 str_instr "(" "'foo@host (dev,web)'" | assert_eq 11
 str_instr ")" "'foo@host (dev,web)'" | assert_eq 19
 str_instr "[" "'foo@host [dev,web]'" | assert_eq 11
 str_instr "]" "'foo@host [dev,web]'" | assert_eq 19
 str_instr "a" "abc" | assert_eq 1
 str_instr "z" "abc" | assert_eq 0
 str_instr "Eggs" "Green Eggs And Ham" | assert_eq 7
 str_instr "a" "" | assert_eq 0
 str_instr "" "" | assert_eq 0
 str_instr " " "Green Eggs" | assert_eq 6
 str_instr " " " Green " | assert_eq 1
}
</code></pre>

blocks|key|1494437|text|msg="message"

function+check+{
++++echo+$msg+%7C+egrep+[abc]+1>+/dev/null

++++if+[+$?+-ne+1+];
++++then+
++++++++echo+"found"+
++++else+
++++++++echo+"not+found"+
++++fi
}

check|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1494438|这将查找出现a、b或c的任何情况。|unstyled|1494439|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>msg="message"

function check {
 echo $msg | egrep [abc] 1&gt; /dev/null

 if [ $? -ne 1 ];
 then 
 echo "found" 
 else 
 echo "not found" 
 fi
}

check
</code></pre>

This will find any occurance of a or b or c

I have a string in Bash:
<pre class="lang-sh prettyprint-override"><code>string=&quot;My string&quot;
</code></pre>
How can I test if it contains another string?
<pre class="lang-sh prettyprint-override"><code>if [ $string ?? 'foo' ]; then
 echo &quot;It's there!&quot;
fi
</code></pre>
Where <code>??</code> is my unknown operator. Do I use <code>echo</code> and <code>grep</code>?
<pre class="lang-sh prettyprint-override"><code>if echo &quot;$string&quot; | grep 'foo'; then
 echo &quot;It's there!&quot;
fi
</code></pre>
That looks a bit clumsy.

How to check if a string contains a substring in Bash

我在Bash中有一个字符串：string="My string"如何测试它是否包含另一个字符串？if [ $string ?? 'foo' ]; then  echo "It's there!"fi其中??是我的未知操作符。我要使用echo和grep吗if echo "$string" | grep 'foo'; then  echo "It's there!"fi这看起来有点笨拙。

问如何检查字符串是否包含Bash中的子字符串
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