Bash =~ operator and tab characters

[Johnny Rosenberg]

2016-04-24 16:31 GMT+02:00 Karl Auer <kauer at biplane.com.au>:

> On Sun, 2016-04-24 at 15:08 +0200, Johnny Rosenberg wrote:
> > I need to check a lot of strings for the following:
> > TAB ( <at least 4 and not more than 10 numbers or minuses> ) TAB
>
> #!/bin/bash
>
> while read LINE ; do
> {
>    if [[ $LINE =~ $'\t'[0-9\-]{4,10}$'\t' ]] ; then
>       echo "$LINE"
>    fi
> }
> done
>
> Redirect or pipe your data into the above script and it will echo all
> matching lines. Not well tested. Note that the regexp does not check
> for formatted dates - just for exactly what you said :-)
>

Well, that's ok. The dates are unfortunately not very consistent. In most
recent cases it's ISO-8601, that is YYYY-MM-DD, but sometimes it's only
YYYY-MM and sometimes even just YYYY.


>
> Obviously you can do whatever else you want inside the if statement.
>
> Oh, and I'm pretty sure the "$'\t'" construct is a bashism.
>

Aaah, yes! I forgot about that one! Thanks for reminding me!


>
> You can't match on tabs nicely in any shell I know of (not that I know
> them all). For heavy duty text processing you are generally better off
> with a language like perl or awk.
>

Unfortunately I don't know much about Perl and I only scratched the surface
of Awk, so I try to use what I know best as much as possible… I know, that
sounds really lazy, but I have other interests in life than just scripting…
:P


Thanks for the help!


Kind regards

Johnny Rosenberg


> Regards, K.
>
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