bash date validate 1

[vodkadrinker]

I am writing a simple script in bash so that it is easily portable, is there an easy way to validate a string is a date?

Example

My string should come back in the format "2013-03-07" CCYY-MM-DD however it may be blank or anything, if it's not in a date format then I would like to ignore it.

if [ $mydatestring == validdate ] ; then
    ...do some stuff...

 

[vodkadrinker]

Found a quick way round this.

if (date --date $mydatestring > /dev/null 2>&1); then

 

[feherke]

Hi

Just to check the format in Bash 3.0 or newer I would prefer :

[teal][[[/teal] [green][i]"$date"[/i][/green] [teal]=~[/teal] [teal]^[[:[/teal]digit[teal]:]][/teal]{[purple]4[/purple]}[teal]([/teal]-[teal][[:[/teal]digit[teal]:]][/teal]{[purple]2[/purple]}[teal])[/teal]{[purple]2[/purple]}$ [teal]]][/teal]

But personally I would allow dates in any format understood by GNU [tt]date[/tt]. ( Systems with Bash usually have such [tt]date[/tt] implementation. ) The following will transform many valid date formats to CCYY-MM-DD and reduces the unknown formats and invalid dates to empty string :

[navy]date[/navy][teal]=[/teal][green][i]"$( date -d '2013-03-07' +'%F' 2> /dev/null )"[/i][/green]
[teal][[[/teal] [green][i]"$date"[/i][/green] [teal]]][/teal] [teal]||[/teal] echo [green][i]'error : missing, invalid or incorrectly formatted date'[/i][/green]

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

 

[vodkadrinker]

Thanks feherke good to know the format option as well, handy for pattern matching things other than dates too.