Bash check java version - not comparing strings properly

Question

Can anyone see what I have done wrong here?

local VERSION=$(java -version 2>&1 | grep "java version")
if [[ ! "$VERSION" =~ *"1.8.0_33"* ]]; then
  ERROR (not code, just place holder)
else
  NO ERROR (not code, just place holder)
fi

Thanks for the quick help!

* UPDATE *

Here is what else I have tried:

local VERSION=$(java -version 2>&1 | grep "java version")
if [[ "$VERSION" != *"1.8.0_33"* ]];  then
  Error blah blah not using 1.8.0_33
else
  Good to go
fi

This is in a function all by itself. No other nested anything.

GNU bash, version 4.2.37(1)-release (arm-unknown-linux-gnueabihf)

Just use: [[ "$VERSION" != *"1.8.0_33"* ]]

anubhava
– anubhava

2015-02-11 17:10:17 +00:00
Commented Feb 11, 2015 at 17:10 — anubhava
– anubhava, Commented Feb 11, 2015 at 17:10
Yes, I tried that as well wth no luck it seems

Atomiklan
– Atomiklan

2015-02-11 17:12:38 +00:00
Commented Feb 11, 2015 at 17:12 — Atomiklan
– Atomiklan, Commented Feb 11, 2015 at 17:12
Have you actually looked to see what $VERSION contains?

arco444
– arco444

2015-02-11 17:13:24 +00:00
Commented Feb 11, 2015 at 17:13 — arco444
– arco444, Commented Feb 11, 2015 at 17:13
What does echo "[$VERSION]" show to you?

anubhava
– anubhava

2015-02-11 17:13:38 +00:00
Commented Feb 11, 2015 at 17:13 — anubhava
– anubhava, Commented Feb 11, 2015 at 17:13
Is java on $PATH when you execute the script?

arco444
– arco444

2015-02-11 17:21:35 +00:00
Commented Feb 11, 2015 at 17:21 — arco444
– arco444, Commented Feb 11, 2015 at 17:21

Etan Reisner · Accepted Answer · 2015-02-11 17:09:42Z

1

The value of VERSION (you shouldn't use ALL_CAPS variables by the way, those are "reserved" for shell/etc. usage) is the entire line that matches 'java version'.

That isn't going to ever match a simple version string.

You need to pull out just the version from the matching line if you want to do something like this.

The RHS of =~ is a regex not a glob. That is you need .* not * to match anything.

Or, as anubhava correctly points out, you can use [[ globbing with != directly.

[[ "$VERSION" != *"\"1.8.0_33\""* ]]

I added escaped quotes to the match since the output from java -version appears to have them and otherwise this would also match 1.8.0_333, etc.

edited Feb 11, 2015 at 17:09

answered Feb 11, 2015 at 17:04

Etan Reisner

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Comments

arco444 · Accepted Answer · 2015-02-11 17:15:43Z

0

Use grep:

VERSION=$(java -version 2>&1 | grep "java version")
if echo "$VERSION" | grep "1.8.0_33";  then
  NO ERROR (not code, just place holder)
else
  ERROR (not code, just place holder)
fi

grep will exit with 0 if outputs any lines, so will execute that in the if, otherwise the code under the else will run.

edited Feb 11, 2015 at 17:15

answered Feb 11, 2015 at 17:06

arco444

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6 Comments

Atomiklan Over a year ago

Nope, this seems to always be true.

arco444 Over a year ago

...? What version of bash / grep are you using?

Etan Reisner Over a year ago

This should work fine (though you might want to use \. to avoid matching non-periods there).

Atomiklan Over a year ago

Everything should be latest

Etan Reisner Over a year ago

Also technically grep exits with zero if it outputs any lines (not it any matched) this is the same for grep but inverted for grep -v.

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