[SOLVED] How to reject uppercase characters in a version number using egrep?

Issue

I have version numbers that look like this:

11.22.33
11.22.33-alpha
11.22.33-beta
11.22.33-beta2

But I need to reject versions with uppercase characters, e.g.

11.22.33-ALPHA     (bad uppercase)
11.22.33-alpha-1   (bad char '-')

I must use egrep.

Here's an example in bash

version=11.22.33-BETA
result=$(echo $version | egrep "[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+(-[0-9a-z]+)?"); echo $result

if [[ -z $result ]]; then
   echo "BAD version!!!"
else
   echo "Good version."
fi

This code doesn't work and outputs "BAD version", with result containing "11.22.33-BETA". What do I need to change?

Solution

egrep has been deprecated.

You may use this regex in grep -E:

grep -E '^[[:digit:]]+(\.[[:digit:]]+){2}(-[a-z]+[[:digit:]]*)?$' file

11.22.33
11.22.33-alpha
11.22.33-beta
11.22.33-beta2

Note use of anchors and quantifiers.

RegEx Details:

• ^: Start
• [[:digit:]]+: Match 1+ digits
• (\.[[:digit:]]+){2}: Match dot followed by 1+ digits. Repeat this group 2 times
• (: Start a group
  • -: Match a -
  • [a-z]+: Match 1+ lowercase letters
  • [[:digit:]]*: Match 0 or more digits
• )?: End group. ? makes this optional match
• $ End

---

You bash script could be like this using -q (quiet) option in grep. Note how we avoid creating a shell variable to store output of grep.

if grep -qE '^[[:digit:]]+(\.[[:digit:]]+){2}(-[a-z]+[[:digit:]]*)?$' <<< "$version"
then
   echo "Good version."
else
   echo "Bad version."
fi

Answered By - anubhava

Answer Checked By - Dawn Plyler (WPSolving Volunteer)