So, I usually write/find a test case generator for any code that I write. This type of code generally leads to some file output. To be thorough, I try and generate many different files to test my code on.

Say the command is like this:

java test <parameters/> > <output filename/>

Is there a way to automate this for many different values of the parameters and generate many different files?

I tried:

for i in seq `0 3`; do java test $i > $i.txt; done

I wasn't able to use the $i in the filename, and without it the command gave me no errors, but did nothing else either. I know the Unix command line is very powerful, and I have a feeling that this should be possible, but I just don't know how to do it.


If you're using Bash, there's no reason to use seq. Also, it's recommended that you use $() instead of backticks (but they're not needed either if you're using one of these forms).

for i in {0..3}; do java test $i > "$i.txt"; done


for ((i=0;i<=3;i++)); do java test $i > "$i.txt"; done

Assuming you are in the bash shell, just move the seq command into the backticks:

for i in `seq 0 3`; do java test $i > $i.txt; done
  • Your solution works as well, but I can select only one correct answer. Dec 7 '10 at 20:16

I would say make your app read stdin and spawn new threads, will be more efficient.

And yet another loop :

seq 0 3 | while read i; do java test $i > "$i.txt"; done

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.