blocks|key|406884|text|可能是这样的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|406885|if+type+-p+java;+then
++++echo+found+java+executable+in+PATH
++++_java=java
elif+[[+-n+"$JAVA_HOME"+]]+&&+[[+-x+"$JAVA_HOME/bin/java"+]];++then
++++echo+found+java+executable+in+JAVA_HOME+++++
++++_java="$JAVA_HOME/bin/java"
else
++++echo+"no+java"
fi

if+[[+"$_java"+]];+then
++++version=$("$_java"+-version+2>&1+%7C+awk+-F+'"'+'/version/+{print+$2}')
++++echo+version+"$version"
++++if+[[+"$version"+>+"1.5"+]];+then
++++++++echo+version+is+more+than+1.5
++++else+++++++++
++++++++echo+version+is+less+than+1.5
++++fi
fi|code-block|syntax|javascript|406886|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|$]]

Perhaps something like:

<pre><code>if type -p java; then
 echo found java executable in PATH
 _java=java
elif [[ -n "$JAVA_HOME" ]] &amp;&amp; [[ -x "$JAVA_HOME/bin/java" ]]; then
 echo found java executable in JAVA_HOME 
 _java="$JAVA_HOME/bin/java"
else
 echo "no java"
fi

if [[ "$_java" ]]; then
 version=$("$_java" -version 2&gt;&amp;1 | awk -F '"' '/version/ {print $2}')
 echo version "$version"
 if [[ "$version" &gt; "1.5" ]]; then
 echo version is more than 1.5
 else 
 echo version is less than 1.5
 fi
fi
</code></pre>

blocks|key|3962603|text|您可以通过以下方式获取java版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3962604|JAVA_VER=$(java+-version+2>&1+%7C+sed+-n+';s/.*+version+"$.*$\.$.*$\..*".*/\1\2/p;')|code-block|syntax|javascript|3962605|它将为您提供1.6.0_13等java版本的16，1.5.0_17等版本的15和openjdk+11.0.6+2020-01-14+LTS版本的110。|offset|length|style|CODE|3962606|因此，您可以很容易地在shell中进行比较：|3962607|[+"$JAVA_VER"+-ge+15+]+&&+echo+"ok,+java+is+1.5+or+newer"+%7C%7C+echo+"it's+too+old..."|3962608|更新：正如注释中提到的，这段代码应该可以很好地与openjdk和JAVA_TOOL_OPTIONS一起工作。|BOLD|3962609|entityMap^0|0|0|6|8|M|2|P|8|11|2|14|T|0|0|0|0|3|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|W|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|X|8|@$I|Y|J|Z|K|L]|$I|10|J|11|K|L]|$I|12|J|13|K|L]|$I|14|J|15|K|L]|$I|16|J|17|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|18|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1A|8|@$I|1B|J|1C|K|S]]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|U|$]]

You can obtain java version via:
<pre><code>JAVA_VER=$(java -version 2&gt;&amp;1 | sed -n ';s/.* version &quot;$.*$\.$.*$\..*&quot;.*/\1\2/p;')
</code></pre>
it will give you <code>16</code> for java like <code>1.6.0_13</code>, <code>15</code> for version like <code>1.5.0_17</code> and 110 for <code>openjdk 11.0.6 2020-01-14 LTS</code>.
So you can easily compare it in shell:
<pre><code>[ &quot;$JAVA_VER&quot; -ge 15 ] &amp;&amp; echo &quot;ok, java is 1.5 or newer&quot; || echo &quot;it's too old...&quot;
</code></pre>
UPDATE:
This code should work fine with openjdk and JAVA_TOOL_OPTIONS as mentioned in comments.

blocks|key|3962786|text|上述答案仅适用于特定的Java版本(通常适用于Java+9之前的版本或Java+8之后的版本。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3962787|我编写了一个简单的一行程序，它将为Java版本6到11返回一个整数(也可能是将来的所有版本，直到它们再次更改它为止！)。|3962788|它基本上去掉了“1”。在版本号的开头，如果它存在，然后只考虑下一个".“之前的第一个数字。|3962789|java+-version+2>&1+%7C+head+-1+%7C+cut+-d'"'+-f2+%7C+sed+'/%5E1\./s///'+%7C+cut+-d'.'+-f1|offset|length|style|CODE|3962790|entityMap^0|0|0|0|0|27|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|P|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|Q|8|@$H|R|I|S|J|K]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|M|$]]

The answers above work correctly only for specific Java versions (usually for the ones before Java 9 or for the ones after Java 8.

I wrote a simple one liner that will return an integer for Java versions 6 through 11 (and possibly all future versions, until they change it again!).

It basically drops the "1." at the beginning of the version number, if it exists, and then considers only the first number before the next ".".

<code>java -version 2&gt;&amp;1 | head -1 | cut -d'"' -f2 | sed '/^1\./s///' | cut -d'.' -f1</code>

blocks|key|4247452|text|您可以发出java+-version命令并读取和解析输出|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4247453|java+-version+2>&1+>/dev/null+%7C+grep+'java+version'+%7C+awk+'{print+$3}'|code-block|syntax|javascript|4247454|entityMap^0|5|D|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You can issue <code>java -version</code> and read &amp; parse the output

<pre><code>java -version 2&gt;&amp;1 &gt;/dev/null | grep 'java version' | awk '{print $3}'
</code></pre>

blocks|key|406943|text|我编写了一个bash函数，它应该适用于JDK9和JDK10。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|406944|#!/bin/bash

#+returns+the+JDK+version.
#+8+for+1.8.0_nn,+9+for+9-ea+etc,+and+"no_java"+for+undetected
jdk_version()+{
++local+result
++local+java_cmd
++if+[[+-n+$(type+-p+java)+]]
++then
++++java_cmd=java
++elif+[[+(-n+"$JAVA_HOME")+&&+(-x+"$JAVA_HOME/bin/java")+]]
++then
++++java_cmd="$JAVA_HOME/bin/java"
++fi
++local+IFS=$'\n'
++#+remove+\r+for+Cygwin
++local+lines=$("$java_cmd"+-Xms32M+-Xmx32M+-version+2>&1+%7C+tr+'\r'+'\n')
++if+[[+-z+$java_cmd+]]
++then
++++result=no_java
++else
++++for+line+in+$lines;+do
++++++if+[[+(-z+$result)+&&+($line+=+*"version+\""*)+]]
++++++then
++++++++local+ver=$(echo+$line+%7C+sed+-e+'s/.*version+"$.*$"$.*$/\1/;+1q')
++++++++#+on+macOS,+sed+doesn't+support+'?'
++++++++if+[[+$ver+=+"1."*+]]
++++++++then
++++++++++result=$(echo+$ver+%7C+sed+-e+'s/1\.$[0-9]*$$.*$/\1/;+1q')
++++++++else
++++++++++result=$(echo+$ver+%7C+sed+-e+'s/$[0-9]*$$.*$/\1/;+1q')
++++++++fi
++++++fi
++++done
++fi
++echo+"$result"
}

v="$(jdk_version)"
echo+$v|code-block|syntax|javascript|406945|这将返回用于Java8的8+("1.8.0_151"等)和用于Java9的9+("9-Debian"等)，这将使进一步的比较变得更容易。|offset|length|style|CODE|406946|entityMap^0|0|0|C|1|F|B|11|1|14|A|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]|$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|N|$]]

I wrote a bash function that should work for JDK 9 and JDK 10.

<pre class="lang-sh prettyprint-override"><code>#!/bin/bash

# returns the JDK version.
# 8 for 1.8.0_nn, 9 for 9-ea etc, and "no_java" for undetected
jdk_version() {
 local result
 local java_cmd
 if [[ -n $(type -p java) ]]
 then
 java_cmd=java
 elif [[ (-n "$JAVA_HOME") &amp;&amp; (-x "$JAVA_HOME/bin/java") ]]
 then
 java_cmd="$JAVA_HOME/bin/java"
 fi
 local IFS=$'\n'
 # remove \r for Cygwin
 local lines=$("$java_cmd" -Xms32M -Xmx32M -version 2&gt;&amp;1 | tr '\r' '\n')
 if [[ -z $java_cmd ]]
 then
 result=no_java
 else
 for line in $lines; do
 if [[ (-z $result) &amp;&amp; ($line = *"version \""*) ]]
 then
 local ver=$(echo $line | sed -e 's/.*version "$.*$"$.*$/\1/; 1q')
 # on macOS, sed doesn't support '?'
 if [[ $ver = "1."* ]]
 then
 result=$(echo $ver | sed -e 's/1\.$[0-9]*$$.*$/\1/; 1q')
 else
 result=$(echo $ver | sed -e 's/$[0-9]*$$.*$/\1/; 1q')
 fi
 fi
 done
 fi
 echo "$result"
}

v="$(jdk_version)"
echo $v
</code></pre>

This returns <code>8</code> for Java 8 (<code>"1.8.0_151"</code> etc), and <code>9</code> for Java 9 (<code>"9-Debian"</code> etc), which should make it easier to do the further comparison.

blocks|key|406919|text|不同答案的组合：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|406920|JAVA_VER=$(java+-version+2>&1+%7C+grep+-i+version+%7C+sed+'s/.*version+".*\.$.*$\..*"/\1/;+1q')|code-block|syntax|javascript|406921|406922|返回适用于Java7的7和适用于Java8的8+|unordered-list-item|offset|length|style|CODE|406923|适用于OpenJDK和Oracle+JDK|406924|即使设置了JAVA_TOOL_OPTIONS也可以使用|406925|406926|entityMap^0|0|0|0|B|1|M|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|W|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|Y|8|@$K|Z|L|10|M|N]|$K|11|L|12|M|N]]|9|@]|A|$]]|$1|O|3|P|5|J|7|13|8|@]|9|@]|A|$]]|$1|Q|3|R|5|J|7|14|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|15|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|U|$]]

A combination of different answers:

<pre><code>JAVA_VER=$(java -version 2&gt;&amp;1 | grep -i version | sed 's/.*version ".*\.$.*$\..*"/\1/; 1q')
</code></pre>

<ul>
<li>Returns <code>7</code> for Java 7 and <code>8</code> for Java 8</li>
<li>Works with OpenJDK and with Oracle JDK</li>
<li>Works even if the JAVA_TOOL_OPTIONS is set</li>
</ul>

blocks|key|3962844|text|您还可以将jdk类版本号与javap进行比较。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3962845|javap+-verbose+java.lang.String+%7C+grep+"major+version"+%7C+cut+-d+"+"+-f5|code-block|syntax|javascript|3962846|如果是java+8，则打印52，如果是java+11，则打印55。这样，您可以进行简单的比较，而不必处理版本字符串解析。|3962847|entityMap^0|D|5|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

You could also compare the jdk class version number with <code>javap</code>:

<pre><code>javap -verbose java.lang.String | grep "major version" | cut -d " " -f5
</code></pre>

If its java 8, this will print 52, and 55 for java 11. With this you can make a simple comparison and you don't have to deal with the version string parsing.

blocks|key|405359|text|我最终使用的方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|405360|#+Work+out+the+JAVA+version+we+are+working+with:
JAVA_VER_MAJOR=""
JAVA_VER_MINOR=""
JAVA_VER_BUILD=""

#+Based+on:+http://stackoverflow.com/a/32026447
for+token+in+$(java+-version+2>&1+%7C+grep+-i+version)
do
++++if+[[+$token+=~+\"([[:digit:]])\.([[:digit:]])\.(.*)\"+]]
++++then
++++++++JAVA_VER_MAJOR=${BASH_REMATCH[1]}
++++++++JAVA_VER_MINOR=${BASH_REMATCH[2]}
++++++++JAVA_VER_BUILD=${BASH_REMATCH[3]}
++++++++break
++++fi
done|code-block|syntax|javascript|405361|即使由于grep进行了过滤而将JAVA_TOOL_OPTIONS设置为某个值，它也会正常工作。|405362|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|$]]

The method I ended up using is:

<pre><code># Work out the JAVA version we are working with:
JAVA_VER_MAJOR=""
JAVA_VER_MINOR=""
JAVA_VER_BUILD=""

# Based on: http://stackoverflow.com/a/32026447
for token in $(java -version 2&gt;&amp;1 | grep -i version)
do
 if [[ $token =~ \"([[:digit:]])\.([[:digit:]])\.(.*)\" ]]
 then
 JAVA_VER_MAJOR=${BASH_REMATCH[1]}
 JAVA_VER_MINOR=${BASH_REMATCH[2]}
 JAVA_VER_BUILD=${BASH_REMATCH[3]}
 break
 fi
done
</code></pre>

It will work correctly even if JAVA_TOOL_OPTIONS is set to something due to filtering done by grep.

blocks|key|3962810|text|终端中的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3962811|ordered-list-item|3962812|3962813|java+-version+%7C&+grep+'version'+%7C&+awk+-F\"+'{+split($2,a,".");+print+a[1]"."a[2]}'|code-block|syntax|javascript|3962814|BASH中的|3962815|3962816|3962817|#!/bin/bash


echo+`java+-version+2>&1+%7C+grep+'version'+2>&1+%7C+awk+-F\"+'{+split($2,a,".");+print+a[1]"."a[2]}'`
jver=`java+-version+2>&1+%7C+grep+'version'+2>&1+%7C+awk+-F\"+'{+split($2,a,".");+print+a[1]"."a[2]}'`

if+[[+$jver+==+"1.8"+]];+then++++++++++++++++
+++++echo+$jver+is+java+8
else
+++++echo+$jver+is+java+11
fi|3962818|在SUN和Linux中工作|3962819|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|-4|5|C|7|U|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|V|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|W|8|@]|9|@]|A|$H|I]]|$1|J|3|K|5|6|7|X|8|@]|9|@]|A|$]]|$1|L|3|-4|5|C|7|Y|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|N|3|O|5|G|7|10|8|@]|9|@]|A|$H|I]]|$1|P|3|Q|5|6|7|11|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|S|$]]

<ol>
<li>in TERMINAL</li>
</ol>

<pre><code>java -version |&amp; grep 'version' |&amp; awk -F\" '{ split($2,a,"."); print a[1]"."a[2]}'
</code></pre>

<ol start="2">
<li>in BASH</li>
</ol>

<pre><code>#!/bin/bash


echo `java -version 2&gt;&amp;1 | grep 'version' 2&gt;&amp;1 | awk -F\" '{ split($2,a,"."); print a[1]"."a[2]}'`
jver=`java -version 2&gt;&amp;1 | grep 'version' 2&gt;&amp;1 | awk -F\" '{ split($2,a,"."); print a[1]"."a[2]}'`

if [[ $jver == "1.8" ]]; then 
 echo $jver is java 8
else
 echo $jver is java 11
fi
</code></pre>

Works in SUN and Linux

blocks|key|407041|text|另一种方法是:在$JAVA_HOME中有一个名为release的文件。在Java+15+(Debian)上，它有如下内容：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|407042|IMPLEMENTOR="Debian"
JAVA_VERSION="15.0.1"
JAVA_VERSION_DATE="2020-10-20"
MODULES="java.base+java.compiler+java.datatransfer+java.xml+java.prefs+java.desktop+java.instrument+java.logging+java.management+java.security.sasl+java.naming+java.rmi+java.management.rmi+java.net.http+java.scripting+java.security.jgss+java.transaction.xa+java.sql+java.sql.rowset+java.xml.crypto+java.se+java.smartcardio+jdk.accessibility+jdk.internal.vm.ci+jdk.management+jdk.unsupported+jdk.internal.vm.compiler+jdk.aot+jdk.internal.jvmstat+jdk.attach+jdk.charsets+jdk.compiler+jdk.crypto.ec+jdk.crypto.cryptoki+jdk.dynalink+jdk.internal.ed+jdk.editpad+jdk.hotspot.agent+jdk.httpserver+jdk.incubator.foreign+jdk.internal.opt+jdk.jdeps+jdk.jlink+jdk.incubator.jpackage+jdk.internal.le+jdk.internal.vm.compiler.management+jdk.jartool+jdk.javadoc+jdk.jcmd+jdk.management.agent+jdk.jconsole+jdk.jdwp.agent+jdk.jdi+jdk.jfr+jdk.jshell+jdk.jsobject+jdk.jstatd+jdk.localedata+jdk.management.jfr+jdk.naming.dns+jdk.naming.rmi+jdk.net+jdk.nio.mapmode+jdk.sctp+jdk.security.auth+jdk.security.jgss+jdk.unsupported.desktop+jdk.xml.dom+jdk.zipfs"
OS_ARCH="x86_64"
OS_NAME="Linux"
SOURCE=""|code-block|syntax|javascript|407043|所以您可以看到JAVA_VERSION，它包含版本号。|407044|例如,|407045|major=$(echo+$JAVA_VERSION+%7C+cut+-d.+-f1)|407046|将major设置为值15+(=主版本号)，您可以进一步使用该值。|407047|这是一个非常简单的解决方案。|407048|entityMap^0|8|A|O|7|0|0|7|C|0|0|0|1|5|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|15|8|@]|D|@]|E|$]]|$1|O|3|P|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|S|3|T|5|6|7|1A|8|@]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|V|$]]

Another way is:
A file called <code>release</code> is located in <code>$JAVA_HOME</code>.
On Java 15 (Debian) it has as content:
<pre><code>IMPLEMENTOR=&quot;Debian&quot;
JAVA_VERSION=&quot;15.0.1&quot;
JAVA_VERSION_DATE=&quot;2020-10-20&quot;
MODULES=&quot;java.base java.compiler java.datatransfer java.xml java.prefs java.desktop java.instrument java.logging java.management java.security.sasl java.naming java.rmi java.management.rmi java.net.http java.scripting java.security.jgss java.transaction.xa java.sql java.sql.rowset java.xml.crypto java.se java.smartcardio jdk.accessibility jdk.internal.vm.ci jdk.management jdk.unsupported jdk.internal.vm.compiler jdk.aot jdk.internal.jvmstat jdk.attach jdk.charsets jdk.compiler jdk.crypto.ec jdk.crypto.cryptoki jdk.dynalink jdk.internal.ed jdk.editpad jdk.hotspot.agent jdk.httpserver jdk.incubator.foreign jdk.internal.opt jdk.jdeps jdk.jlink jdk.incubator.jpackage jdk.internal.le jdk.internal.vm.compiler.management jdk.jartool jdk.javadoc jdk.jcmd jdk.management.agent jdk.jconsole jdk.jdwp.agent jdk.jdi jdk.jfr jdk.jshell jdk.jsobject jdk.jstatd jdk.localedata jdk.management.jfr jdk.naming.dns jdk.naming.rmi jdk.net jdk.nio.mapmode jdk.sctp jdk.security.auth jdk.security.jgss jdk.unsupported.desktop jdk.xml.dom jdk.zipfs&quot;
OS_ARCH=&quot;x86_64&quot;
OS_NAME=&quot;Linux&quot;
SOURCE=&quot;&quot;
</code></pre>
So you see <code>JAVA_VERSION</code>, which contains the version number.
For example,
<pre><code>major=$(echo $JAVA_VERSION | cut -d. -f1)
</code></pre>
sets <code>major</code> to the value 15 (=Major version number), which you can use further.
It's a really simple solution.

blocks|key|3962769|text|我遇到了一个类似的问题，我想检查一下安装了哪个版本的java来执行两种类型的应用程序启动。下面的代码解决了我的问题|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3962770|jdk_version()+{
++local+result
++local+java_cmd
++if+[[+-n+$(type+-p+java)+]]
++then
++++java_cmd=java
++elif+[[+(-n+"$JAVA_HOME")+&&+(-x+"$JAVA_HOME/bin/java")+]]
++then
++++java_cmd="$JAVA_HOME/bin/java"
++fi
++local+IFS=$'\n'
++#+remove+\r+for+Cygwin
++local+lines=$("$java_cmd"+-Xms32M+-Xmx32M+-version+2>&1+%7C+tr+'\r'+'\n')
++if+[[+-z+$java_cmd+]]
++then
++++result=no_java
++else
++++for+line+in+$lines;+do
++++++if+[[+(-z+$result)+&&+($line+=+*"version+\""*)+]]
++++++then
++++++++local+ver=$(echo+$line+%7C+sed+-e+'s/.*version+"$.*$"$.*$/\1/;+1q')
++++++++#+on+macOS,+sed+doesn't+support+'?'
++++++++if+[[+$ver+=+"1."*+]]
++++++++then
++++++++++result=$(echo+$ver+%7C+sed+-e+'s/1\.$[0-9]*$$.*$/\1/;+1q')
++++++++else
++++++++++result=$(echo+$ver+%7C+sed+-e+'s/$[0-9]*$$.*$/\1/;+1q')
++++++++fi
++++++fi
++++done
++fi
++echo+"$result"
}

_java="$(jdk_version)"
echo+$_java

if+[[+"$_java"+>+"$8"+]];+then
+++++++echo+version+is+more+than+8

else
++echo+version+is+less+than+8

fi|code-block|syntax|javascript|3962771|source|offset|length|3962772|我希望被证明是有帮助的|3962773|entityMap|0|LINK|mutability|MUTABLE|url|http://eed3si9n.com/detecting-java-version-bash^0|0|0|0|6|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

I had a similar problem, I wanted to check which version of java was installed to perform two types of application launches.
The following code has solved my problem

<pre><code>jdk_version() {
 local result
 local java_cmd
 if [[ -n $(type -p java) ]]
 then
 java_cmd=java
 elif [[ (-n "$JAVA_HOME") &amp;&amp; (-x "$JAVA_HOME/bin/java") ]]
 then
 java_cmd="$JAVA_HOME/bin/java"
 fi
 local IFS=$'\n'
 # remove \r for Cygwin
 local lines=$("$java_cmd" -Xms32M -Xmx32M -version 2&gt;&amp;1 | tr '\r' '\n')
 if [[ -z $java_cmd ]]
 then
 result=no_java
 else
 for line in $lines; do
 if [[ (-z $result) &amp;&amp; ($line = *"version \""*) ]]
 then
 local ver=$(echo $line | sed -e 's/.*version "$.*$"$.*$/\1/; 1q')
 # on macOS, sed doesn't support '?'
 if [[ $ver = "1."* ]]
 then
 result=$(echo $ver | sed -e 's/1\.$[0-9]*$$.*$/\1/; 1q')
 else
 result=$(echo $ver | sed -e 's/$[0-9]*$$.*$/\1/; 1q')
 fi
 fi
 done
 fi
 echo "$result"
}

_java="$(jdk_version)"
echo $_java

if [[ "$_java" &gt; "$8" ]]; then
 echo version is more than 8

else
 echo version is less than 8

fi
</code></pre>

<a href="http://eed3si9n.com/detecting-java-version-bash" rel="nofollow noreferrer">source</a>

I hope to be proved helpful

blocks|key|3962875|text|这里有一个很好的可移植的bash函数：http://eed3si9n.com/detecting-java-version-bash|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3962876|jdk_version()+{
++local+result
++local+java_cmd
++if+[[+-n+$(type+-p+java)+]]
++then
++++java_cmd=java
++elif+[[+(-n+"$JAVA_HOME")+&&+(-x+"$JAVA_HOME/bin/java")+]]
++then
++++java_cmd="$JAVA_HOME/bin/java"
++fi
++local+IFS=$'\n'
++#+remove+\r+for+Cygwin
++local+lines=$("$java_cmd"+-Xms32M+-Xmx32M+-version+2>&1+%7C+tr+'\r'+'\n')
++if+[[+-z+$java_cmd+]]
++then
++++result=no_java
++else
++++for+line+in+$lines;+do
++++++if+[[+(-z+$result)+&&+($line+=+*"version+\""*)+]]
++++++then
++++++++local+ver=$(echo+$line+%7C+sed+-e+'s/.*version+"$.*$"$.*$/\1/;+1q')
++++++++#+on+macOS,+sed+doesn't+support+'?'
++++++++if+[[+$ver+=+"1."*+]]
++++++++then
++++++++++result=$(echo+$ver+%7C+sed+-e+'s/1\.$[0-9]*$$.*$/\1/;+1q')
++++++++else
++++++++++result=$(echo+$ver+%7C+sed+-e+'s/$[0-9]*$$.*$/\1/;+1q')
++++++++fi
++++++fi
++++done
++fi
++echo+"$result"
}|code-block|syntax|javascript|3962877|entityMap|0|LINK|mutability|MUTABLE|url|http://eed3si9n.com/detecting-java-version-bash^0|J|1B|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]]]]

There is a nice portable bash function for this here: <a href="http://eed3si9n.com/detecting-java-version-bash" rel="nofollow noreferrer">http://eed3si9n.com/detecting-java-version-bash</a>
<pre><code>jdk_version() {
 local result
 local java_cmd
 if [[ -n $(type -p java) ]]
 then
 java_cmd=java
 elif [[ (-n &quot;$JAVA_HOME&quot;) &amp;&amp; (-x &quot;$JAVA_HOME/bin/java&quot;) ]]
 then
 java_cmd=&quot;$JAVA_HOME/bin/java&quot;
 fi
 local IFS=$'\n'
 # remove \r for Cygwin
 local lines=$(&quot;$java_cmd&quot; -Xms32M -Xmx32M -version 2&gt;&amp;1 | tr '\r' '\n')
 if [[ -z $java_cmd ]]
 then
 result=no_java
 else
 for line in $lines; do
 if [[ (-z $result) &amp;&amp; ($line = *&quot;version \&quot;&quot;*) ]]
 then
 local ver=$(echo $line | sed -e 's/.*version &quot;$.*$&quot;$.*$/\1/; 1q')
 # on macOS, sed doesn't support '?'
 if [[ $ver = &quot;1.&quot;* ]]
 then
 result=$(echo $ver | sed -e 's/1\.$[0-9]*$$.*$/\1/; 1q')
 else
 result=$(echo $ver | sed -e 's/$[0-9]*$$.*$/\1/; 1q')
 fi
 fi
 done
 fi
 echo &quot;$result&quot;
}
</code></pre>

blocks|key|405546|text|只使用带有Perl风格的regex的grep可以确定Java版本，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|405547|java+-version+2>&1+%7C+grep+-oP+'version+"?(1\.)?\K\d%2B'|code-block|syntax|javascript|405548|这将打印Java9或更高版本的主要版本，以及低于9的版本的次要版本，例如用于Java+1.8的8和用于Java+11.0.4的11。|offset|length|style|CODE|405549|它可以像这样使用：|405550|JAVA_MAJOR_VERSION=$(java+-version+2>&1+%7C+grep+-oP+'version+"?(1\.)?\K\d%2B'+%7C%7C+true)
if+[[+$JAVA_MAJOR_VERSION+-lt+8+]];+then
++echo+"Java+8+or+higher+is+required!"
++exit+1
fi|405551|添加%7C%7C+true是为了防止脚本在未安装Java且启用了外壳选项set+-e的情况下中止。|405552|entityMap^0|0|0|17|3|1B|1|1K|6|1R|2|0|0|0|2|7|W|6|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|16|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|17|8|@$I|18|J|19|K|L]|$I|1A|J|1B|K|L]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|T|$]]

Determining the Java version only using grep with Perl-style regex can be done like this:
<pre class="lang-sh prettyprint-override"><code>java -version 2&gt;&amp;1 | grep -oP 'version &quot;?(1\.)?\K\d+'
</code></pre>
This will print the major version for Java 9 or higher and the minor version for versions lower than 9, for example <code>8</code> for Java <code>1.8</code> and <code>11</code> for Java <code>11.0.4</code>.
It can be used like this:
<pre class="lang-sh prettyprint-override"><code>JAVA_MAJOR_VERSION=$(java -version 2&gt;&amp;1 | grep -oP 'version &quot;?(1\.)?\K\d+' || true)
if [[ $JAVA_MAJOR_VERSION -lt 8 ]]; then
 echo &quot;Java 8 or higher is required!&quot;
 exit 1
fi
</code></pre>
The <code>|| true</code> was added to prevent the script from aborting in case Java is not installed and the Shell option <code>set -e</code> was enabled.

blocks|key|2348127|text|使用bashj，一个扩展的bash版本(https://sourceforge.net/projects/bashj/)，您可以得到一个相当紧凑的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2348128|#!/usr/bin/bashj
echo+System.getProperty("java.runtime.version")|code-block|syntax|javascript|2348129|答案由一个集成的JVM提供(脚本的执行时间约为0.017“，调用本身的执行时间约为0.004”)。|2348130|entityMap|0|LINK|mutability|MUTABLE|url|https://sourceforge.net/projects/bashj/^0|K|13|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

Using bashj, an extended bash version (<a href="https://sourceforge.net/projects/bashj/" rel="nofollow noreferrer">https://sourceforge.net/projects/bashj/</a>), you get a rather compact solution:

<pre><code>#!/usr/bin/bashj
echo System.getProperty("java.runtime.version")
</code></pre>

The answer is provided by an integrated JVM (in ~0.017'' execution time for the script , and ~0.004'' for the call itself).

blocks|key|405533|text|我发现下面的方法运行得相当好。它综合了Michał+Šrajer和jmj的答案|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|405534|version=$(java+-version+2>&1+%7C+sed+-n+';s/.*+version+"$.*$\.$.*$\..*"/\1\2/p;'+%7C+awk+'{+print+$1+}')。|style|CODE|405535|我已经安装了openJDK+13，并且没有使用awk命令，打印出了第一个答案：130+2020-01-14。因此，添加awk+'{+print+$1+}'为我提供了正确的版本。|405536|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/7335120/4215616|1|https://stackoverflow.com/a/7334780/4215616^0|J|D|0|X|3|1|0|0|2W|0|N|3|13|E|1N|I|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]|$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@$A|11|B|12|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|13|8|@$A|14|B|15|F|G]|$A|16|B|17|F|G]|$A|18|B|19|F|G]]|9|@]|C|$]]|$1|J|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]|R|$5|M|N|O|C|$P|S]]]]

I found the following works rather well. It is a combination of the answers from <a href="https://stackoverflow.com/a/7335120/4215616">Michał Šrajer</a> and <a href="https://stackoverflow.com/a/7334780/4215616">jmj</a>
<code>version=$(java -version 2&gt;&amp;1 | sed -n ';s/.* version &quot;$.*$\.$.*$\..*&quot;/\1\2/p;' | awk '{ print $1 }')</code>.
I have openJDK 13 installed and without the <code>awk</code> command the first answer printed: <code>130 2020-01-14</code>. Thus, adding <code>awk '{ print $1 }'</code> provides me with just the version.

How can I check whether Java is available (in the PATH or via JAVA_HOME) from a bash script and make sure the version is at least 1.5?

Correct way to check Java version from BASH script

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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如何从bash脚本检查Java是否可用(在PATH中或通过JAVA_HOME)，并确保版本至少为1.5？

问从BASH脚本检查Java版本的正确方法
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