title: How to write and match regular expressions in /bin/sh script?
body: <p>I am writing a shell script for a limited unix-based microkernel which doesn't have bash! the /bin/sh can't run the following lines for some reasons.</p>
  
  <pre><code>if [[ `uname` =~ (QNX|qnx) ]]; then
  read -p "what is the dev prefix to use? " dev_prefix
  if [[ $dev_prefix =~ ^[a-z0-9_-]+@[a-z0-9_-"."]+:.*$ ]]; then
  </code></pre>
  
  <p>For the 1st and 3rd lines, it complains about missing expression operator, and for the 2nd line it says no coprocess! Can anyone shed light on differences between /bin/bash and /bin/sh scripts?</p>