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quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean

Terminal - quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean
echo 2006-10-10 | grep -c '^[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]$'
2009-05-11 22:18:43
User: rez0r
Functions: echo grep
-1
quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean

Quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean, the regex can easily be upgraded to handle "in betweens" for mm dd or to validate other types of strings, ex. ip address.

Boolean output could easily be piped into a condition for a more complete one-liner.

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
if date -d 2006-10-10 >> /dev/null 2>&1; then echo 1; else echo 0; fi
2013-01-10 10:35:15
Functions: date echo
0

On CentOS at least, date returns a boolean for the common date string formats, including YYYY-MM-DD. In the sample output, you can see various invalid dates returning 0 whereas a simple regex check would return 1 for the invalid dates.

-d, --date=STRING display time described by STRING, not `now'

The version of date on OS X does not appear to have this same option.

Know a better way?

If you can do better, submit your command here.

What others think

You can reduse repetitious typing using 1 of the following commands and achieve the same result :).

echo 2006-10-10 |egrep -c '^[0-9]{4}-[0-9]\{2\}-[0-9]\{2\}'

OR

echo 2006-10-10 |egrep -c '^[0-9]{4}-[0-9]{2}-[0-9]{2}'

Comment by scifisamurai 292 weeks and 6 days ago

Aghh, correction - the 1st line should have been:

echo 2006-10-10 |grep -c '^[0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}'

I wish commandlinefu had a delete option for one's own posts/comments to clean up one's own typos.

Comment by scifisamurai 292 weeks and 6 days ago

nice:)

Comment by rez0r 292 weeks and 4 days ago

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