Question:
How to validate date column in a file using regular expression in awk ?? My code doesn’t seem to be working with awk.my code
Answer:
InGNU awk the \d and \z sequences are not valid regex operators (a quick web search doesn’t show these as valid regex operators in a couple others flavors of awk though by no means an exhaustive search).I’d suggest replacing the
\d with [0-9] or [[:digit:]]; as for the \z you could try \> or \y.One other issue is the use of
. as a wildcard match in the time component; if you know all times will use a colon (:) as a delimiter then I’d use an explicit colon.Rolling these changes into the current code (and fixing a couple cut-n-paste/syntax issues):
- obviously (?) this code assumes a specific date/time format and thus …
- this code will not match on other valid date/time formats (eg, won’t match on
2021/12/31) - the use of
[0-9]opens you up to matching on strings that are not valid dates and/or times, eg, this code will match on99/99/2022and99:99:99); OP can address some of these by limiting the series of digits that can be matched in a given position (eg,[0-2][0-9]for hours) but even this is problematic since29will match but is not a valid hour - as alluded to in comments … validating dates/times is doable but will require a good bit more code (alternatively run a web search on
bash awk validate dates timesfor additional ideas)
If you have better answer, please add a comment about this, thank you!