How to check if a string contains version in numberic/decimal format in shell script
for eg we have 1.2.3.5 or 2.3.5
What if we do not have a constraint on the number of characters we have in here. It could x.x.x.x or x.x as well.
3
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1A regular expression?Oliver Charlesworth– Oliver Charlesworth2013-06-12 01:30:17 +00:00Commented Jun 12, 2013 at 1:30
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1Do you care about -alpha versions, RC versions, -stable versions, etc?000– 0002013-06-12 01:30:37 +00:00Commented Jun 12, 2013 at 1:30
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Hope that your script doesn't contain IP addresses.devnull– devnull2013-06-12 04:49:12 +00:00Commented Jun 12, 2013 at 4:49
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4 Answers
If you're using bash, you can use the =~ regex match binary operator, for example:
pax> if [[ 1.x20.3 =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]] ; then echo yes ; fi
pax> if [[ 1.20.3 =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]] ; then echo yes ; fi
yes
For your particular test data, the following regex will do the trick:
^[0-9]+(\.[0-9]+)*$
(a number followed by any quantity of .<number> extensions) although, if you want to handle edge cases like 1.2-rc7 or 4.5-special, you'll need something a little more complex.
Comments
Using bash regular expressions:
echo -n "Test: "
read i
if [[ $i =~ ^[0-9]+(\.[0-9]+){2,3}$ ]];
then
echo Yes
fi
This accepts digits.digits.digits or digits.digits.digits.digits
Change {2,3} to shrink or enlarge the acceptable number of .digits (or {2,} for "at least 2")
^means beginning of string[0-9]+means at least one digit\.is a dot(...){2,3}accepts 2 or 3 of what's inside the()$means end of string
2 Comments
glenn jackman
You could use
{2,} to remove the upper bound: 1.2.3.4.5.6.7.8
Déjà vu
@glennjackman Thanks. Re the question, it seems to be 3 or 4 numbers, but, indeed, that could be at least 2 (+1, the first)
And if you're truly restricted to the Bourne shell, then use expr:
if expr 1.2.3.4.5 : '^[0-9][.0-9]*[0-9]$' > /dev/null; then
echo "yep, it's a version number"
fi
I'm sure there are solutions involving awk or sed, but this will do.
1 Comment
Edward Falk
Actually, this would accept "1..2", which might not be acceptable to you.
Flip the logic: check if it contains an "invalid" character:
$ str=1.2.3.4.5; [[ $str == *[^0-9.]* ]] && echo nope || echo yup
yup
$ str=123x4.5; [[ $str == *[^0-9.]* ]] && echo nope || echo yup
nope
Downside to this answer:
$ str=123....; [[ $str == *[^0-9.]* ]] && echo nope || echo yup
yup
