"which java" in CentOS prints wrong java path

Question

I am not sure why "which java" and "whereis java" paths are not correct. I tried to edit ~/.bash_profile and /etc/environment but did not help. The desired path is what is seen in "echo $JAVA_HOME" below but the same is not reflected in "which java"

Below is what I get in CentOS 6.4:

which java

/usr/bin/java

---

java -version

java version "1.7.0_45"

JAVA(TM) SE Runtime Environment (build 1.7.0_45-b18)

JAVA HotSpot (TM) 64-bit Server VM (build 24.45-b08, mixed mode)

---

whereis java

java: /usr/bin/java /etc/java /usr/lib/java /usr/share/java

---

echo $JAVA_HOME

/usr/java/jdk1.7.0_45/jre => desired shows correct when echo $JAVA_HOME

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Solution 1

Run alternatives --config java to pick the Java version you want to use as default. It will print out a list of installed Javas to choose from.

which java, however, will always print out /usr/bin/java. This doesn't mean it's set wrong! Observe:

$ ls -l `which java`
lrwxrwxrwx 1 root root 22 Oct 19 11:49 /usr/bin/java -> /etc/alternatives/java
$ ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 35 Oct 19 11:49 /etc/alternatives/java -> /usr/lib/jvm/jre-1.5.0-gcj/bin/java

If you use alternatives to change the path to IcedTea, ls -l /etc/alternatives/java will reflect that.

Solution 2

Your PATH (and nothing else) determines which directories to look for commands. This is the same in Linux, Solaris, and DOS.

When you do a which {command} it find the first directory you can execute the command in.

When you update your PATH in .bashrc, you have to source it again to change your current settings.

Comments

[sunskin]

i tried "source ~/.bashrc" as root after editing bashrc and it gave me "bash: export: '/usr/java/jdk1.7.0_45/jre=/usr/java/jdk1.7.0_45/jre' : not a valid identifier

[sunskin]

i tried it already shows the desired one as selected but why it does not reflect in "which java"

[Vishy]

That means you have a syntax error in your .bashrc. My bet is you have written something like $JAVA_HOME=/usr/java/jdk1.7.0_45/jre Remove the $ BTW This won't change your PATH which is what matters for which

[sunskin]

Great! Thank you. I never thought of that was symlinked to actual java. I was always in an impression that "which java" is printing wrong

[sunskin]

+1 thanks peter. that helped but I had to accept Henry answer as he provided an explanation of why 'which java' is pointing to a location which I misunderstood

[sunskin]

one correction, I had to do ls -l /usr/bin/java instead of ls -l 'which java' but nevertheless thanks for your help. Hav a good one!

[Henry Finucane]

Those are backticks, not single quotes, which evaluate to '/usr/bin/java' before the ls command is run. Shell magic :)

[twobob]

thanks Peter, this was driving me crazy, I simply prefixed the 1.6 bin path to the PATH environment variable, relogged and now "which" works as expected. I make a note of this here as this is now required for building the android sources. Appreciated.

[nuicca]

Thanks alot, its always a mess configuring and understanding these java paths