title: How to make a regex case sensitive
body: <p>I have a below regex and want that it only accepts case sensitive chars, what should i change it to </p>
  
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>msg_regex='ABC-[0-9]+|DEF-[0-9]+|GHI-[0-9]+'</code></pre>
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  <p>Its used in the below shell script  :-</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>#!/bin/bash
  set -e
  
  zero_commit='0000000000000000000000000000000000000000'
  msg_regex='ABC-[0-9]+|DEF-[0-9]+|GHE-[0-9]+'
  
  while read -r oldrev newrev refname; do
  
   # Branch or tag got deleted, ignore the push
      [ "$newrev" = "$zero_commit" ] &amp;&amp; continue
  
      # Calculate range for new branch/updated branch
      [ "$oldrev" = "$zero_commit" ] &amp;&amp; range="$newrev" || range="$oldrev..$newrev"
  
   for commit in $(git rev-list "$range" --not --all); do
    if ! git log --max-count=1 --format=%B $commit | grep -iqE "$msg_regex"; then
     echo "ERROR:"
     echo "ERROR: Your push was rejected because the commit"
     echo "ERROR: $commit in ${refname#refs/heads/}"
     echo "ERROR: is missing the JIRA Issue"
     echo "ERROR:"
     echo "ERROR: Please fix the commit message and push again."
     echo "ERROR: https://confluence.ameren.com/display/PUBLIC/Checking+Commit+Message+For+JIRA+Issue+Number"
     echo "ERROR"
     exit 1
    fi
   done
  
  done</code></pre>
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  <p>Looks like the grep in the below is ignoring the case :-</p>
  
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>if ! git log --max-count=1 --format=%B $commit | grep -iqE "$msg_regex"</code></pre>
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  <p>Right now it gets evaluated for lower case abc, def and ghi also.</p>
  
  <p>I would like that it only allows ABC, DEF and GHI uppercase but at the same be able to accept any number from 0 to infinite in the format ABC-number or DEF-number or GHI-number</p>
  
  <p>Please suggest!</p>