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String regex comparisons

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# 1  
Old 11-18-2014
String regex comparisons
Here is the sample code:
Code:
str1="abccccc"
str2="abc?"
if [[ $str1 =~ $str2 ]]; then
  echo "same string"
else
  echo "different string"
fi

Given that ? implies 0 or 1 match of preceding character, I was expecting the output to be "different string", but I am seeing "same string".

Am I not using the regex comparisons in right way?

thanks,
RCK
# 2  
Old 11-18-2014
try it with quotes around your variables;
Code:
if [[ "$str1" =~ "$str2" ]]; then

# 3  
Old 11-19-2014
ongoto: No. Quoting $str2 in this context performs a string comparison instead of an ERE match.

Rameshck: The ERE abc? will match ab or abc appearing anywhere in the expansion of $str1. To match only ab or abc you need to anchor the ERE on both ends:
Code:
str1="abccccc"
str2='^abc?$'
if [[ $str1 =~ $str2 ]]; then
  echo "same string"
else
  echo "different string"
fi

This User Gave Thanks to Don Cragun For This Post:
Rameshck
# 4  
Old 11-19-2014
@ Don Cragun
Aha!
I find that ...
Quote:
the behaviour of the =~ (regex) operator has changed since Bash 3.2
Good catch! Thanks.
This User Gave Thanks to ongoto For This Post:
Rameshck
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