Awk regular expression syntax with number of repetition - different handling between gawk 3 and gawk 4 I am having trouble understanding or explaining why the following expression fails in `gawk 3.1.x` and yet works in gawk `4.1.x`: (Minimum working example) `echo ";#ADCDE#" | awk '/#.{5}#$/'` -> produces a match in `gawk 4.1.x`, does not produce a match in `gawk 3.1.x` `echo ";#ADCDE#" | awk '/#.*#$/'` -> produces a match in both Did something change between gawk 3 and 4 in how regular expressions are handled? I didn't think the repetition construct {n} was new for regular expressions. The same behaviour happens if I change the dot (.) with a character class or [A-Z]

Adding `--posix` works in 3.1


echo ";#ADCDE#" | gawk --posix '/#.{5}#$/'


I have


awk --version
GNU Awk 3.1.6
...


From my `man awk` page


r{n}
r{n,}
r{n,m} One or two numbers inside braces denote an interval expres‐
sion. If there is one number in the braces, the preceding
regular expression r is repeated n times. If there are two
numbers separated by a comma, r is repeated n to m times.
If there is one number followed by a comma, then r is
repeated at least n times.
Interval expressions are only available if either --posix or
--re-interval is specified on the command line.