[GRLUG] Bash regex

[Nathan Phillip Brink]

On Tue, May 07, 2013 at 01:21:35PM -0500, L. V. Lammert wrote:
> > See ^^$ info '(bash)Conditional Constructs'^^ which, in explaining the
> > regex ^^=~^^ operator, says ^^Any part of the pattern may be quoted to
> > force it to be matched as a string.^^ Your expression works after
> > removing the single quotes.
> >
> I had tried single, double, as well as no quotes, .. none would match the
> YYYY-MM string when properly formatted.
> 
> I ended up with:
> 
> if [[ ! $1 =~ [0-9][0-9][0-9][0-9]-[0-9][0-9] ]] ; then
>    echo '    Usage: backup YYYY-MM'
>    exit
> fi
> 
> I believe the main problem was the missing 'number' modifier usable in
> bash, so I had to explictly repeat the digits.
> 
> 	Thanks!
> 
> 	Lee

Works for me:

ohnobinki at ohnopublishing ~ $ a=2012-04
ohnobinki at ohnopublishing ~ $ [[ $a =~ [0-9]{4}-[0-9]{2} ]]; echo $?
0
ohnobinki at ohnopublishing ~ $ a=20a2-04
ohnobinki at ohnopublishing ~ $ [[ $a =~ [0-9]{4}-[0-9]{2} ]]; echo $?
1
ohnobinki at ohnopublishing ~ $ echo ${BASH_VERSION}
4.2.10(2)-release

-- 
binki

Look out for missing or extraneous apostrophes!
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