Why does this bash command take up all space on device?

Question

I'm a little new on searching via bash, so feel free to give me suggestions on the methods to use instead of this, which I'll never use again :)

I'm searching for occurances of a string, recursively in a directory, with ~50 not-that-large php-files in it; some in current directory, some in directories beneath current dir, three levels of directories down at most.

The method I'm using is:
find . | xargs grep "module" > module.txt

When in simple (one level) directories, this works fine, but in this case, the file became 4 GB large until it filled up all space on the partition :) It wasn't even done yet..

Would someone educate me so I won't embarass myself again? Feel free to move this to another sibling site, if needed..

Answer 1

module.txt is created before the pipeline starts, therefore it is included in the search. grep finds an instance of "module" in it, so a line is added to it containing the word "module". Which grep then finds, and adds. Which grep then finds, and adds. Which grep then finds, and adds. Which...

Answer 2

And what is the output without > module.txt.

Why not try to use grep -R "module" . > ../module.txt?

Answer 3

find /path -type f -iname "*.php" | while read -r FILE
do
  grep -H "module" "$FILE" >> "file_with_search_term_found.txt"
done

Or if your grep has recursive function,

grep -RH "module" *.php

Or with bash 4.0 shell

shopt -s globstar
for file in /path/**/*.php
do
   if [ -f "$file" ];then
      while read -r line 
      do
         case "$line" in
           *module* ) echo $line >> module.txt;;
         esac    
      done <"file"      
   fi

done