Is grep being used correctly?

Shell Programming and Scripting
1

My goal is to find files contain the "signal 11" string in a specific directory. I need the file details followed by the string.

I wrote a script to test out and play with Shell command since it's my first time to write a Shell script.

Let me cut the story short...

this command line: if [ 'grep -i "signal 11" $fil' -ne "" ]
returns nothing, but actually in reality, I have couple files contains "signal 11" string.

My question is, why does the script not return a list of files which contains "signal 11"?
Is there anything wrong with my script that you can see?

Thanks in advance!

==========================================

#!/bin/sh
#
RESULT=/disk2/app/applmgr/appltop/cssm_custom/11.5.0/out/W2.out
if [ -f /disk2/app/applmgr/appltop/cssm_custom/11.5.0/out/W2.out ]
then
rm $RESULT
fi
#List all modified files more then 7 days in the Directory
for fil in `find /disk2/app/applmgr/comntop/admin/log/ARDEV_arebdd -type f -mtime +7`
do
#Check if the file contains "signal 11"
#If Yes, print out the file name to the output file.
if [ 'grep -i "signal 11" $fil' -ne "" ]
then
echo "fil = $fil" >> $RESULT
fi
done

2 
if grep -ic "signal 11" $fil
then
   echo "fil = $fil" >> $RESULT
fi
3

if your grep supports -l (no need to use if/else )

grep -l  pattern $fil  >>  out

another way

awk '/pattern/{print FILENAME;exit}' $file >> out