Bash - Reasons for stderr to fill up? -

i wrote script works should, reason stderr being filled something. can go in there , how can prevent happening?

here's scripts, gets directory first argument , names of people next x arguments.

#!/bin/bash  authors=$# args=("$@")  ((i = 1; < authors; i++));     echo ${args[${i}]}     d in `find $1 -type d`;         appearances=`grep -c ${args[${i}]} $d/*.comp`         if [ "$appearances" -gt 0 ];             filename=`grep -l ${args[${i}]} $d/*.comp | rev | cut -d '/' -f 1 | rev | cut -d '.' -f 1`             results=`get_test_stats $d | grep -w ${args[${i}]} | cut -d" " -f2-3`             echo $filename: $results         fi     done done 

thank you!

commands find , grep may encounter variety of conditions may unexpected or not reflected in output written stdout. inform user of such condition, warning written stderr, example:

grep: binary file [...] matches find: `[...]': permission denied 

in interactive session, messages written stderr displayed in terminal, if stdout redirected, e.g:

mj@ap:/tmp$ find > results find: `./cron-apt.ex7jhf': permission denied 

or captured in variable, e.g:

mj@ap:/tmp$ results=$( find ) find: `./cron-apt.ex7jhf': permission denied 

you can redirect stderr well:

find >results 2>errorfile  # redirect stderr errorfile find >results 2>/dev/null  # discard stderr find >results 2>&1         # include stderr in results 

respectively:

results=$( find 2>errorfile ) # redirect stderr errorfile results=$( find 2>/dev/null ) # discard stderr results=$( find 2>&1 )        # include stderr in results 

see manpage bash(1) more information on redirection (search redirection).