BASH - grep - works on command line, but not script

Question

I am trying to get the number of occurrences in a script and when running the command on the command line, it works fine, but not in a script. Both variables are initialized. FILE_PATH is the absolute path of the file and VARIABLE_NAME is something like firstName or lastName.

VARIABLE_NAME="_firstName"    
grep -cP "\(this\.|\s\){1}$VARIABLE_NAME" $FILE_PATH

When I take $VARIABLE_NAME out of the script and replace it directly with what I am looking for, it works as expected, so it is something with the replacement.

Any ideas what I can try?

Solution

The problem seems to reside in your regex. can you show us what you are trying to match?

if you are trying to match constructs like this :

this.contentOfVar
  contentOfVar

try it with the following :

grep -cP "(this\.|\s)$VARIABLE_NAME" $FILE_PATH

This works in GNU grep. You don't have to specify {1}, since the default will be 1. With the -P flag on, \( and \) will match literal parenthesis in the string, since this is the perl behavior.

Comments

[garyjohn]

Is that really all that line does in your script, print the number of occurrences to stdout, or is it part of some larger command?

[Walter]

It is part of a larger command, but I cannot get this part to work.