Using for loop with find command

Question

I want to read all java Versions on my system.

for i in 'find / -name java 2>/dev/null' 
do
echo $i checking
$i -version
done

I receive an error:

find: paths must precede expression: 2>/dev/null

Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec] [path...] [expression]

What is the problem?

Answer 1

You're receiving that error from the for loop because your for loop is actually looping over one element -- the string, not the command: "find / -name java 2>/dev/null", so it is running:

echo find / -name java 2>/dev/null checking
find / -name java 2>/dev/null -version

... which is where find's error arises.

You might be trying to do:

for i in `find / -name java 2>/dev/null` 
do
  echo $i checking
  $i -version
done

... (with backticks instead of single quotes), in which case I would suggest something more along the lines of:

find / -name java -exec sh -c '"$1" -version' sh {} \; 2>/dev/null

Thanks to don_crissti for pointing out Stéphane's better version of find ... exec and for indirectly reminding me of a bash method that is one better way to find and execute results than looping over find:

shopt -s globstar dotglob
for match in /**/java
do
  echo match is "$match"
  "$match" -version
done