Re: [Help-bash] group

[John McKown]

On Mon, Dec 12, 2016 at 7:25 AM, Greg Wooledge <address@hidden> wrote:

> On Sat, Dec 10, 2016 at 07:52:22PM +0000, Val Krem wrote:
> > The file names look like as follow.
> > Region-19940726.csv
> > Region-19940816.csv
> > Region-19940920.csv
> > Region-19941018.csv
> > Region-19941122.csv
> > Region.csv
> > RegionAB-19940726.csv
> > RegionAB-19940816.csv
> > RegionAB-19940920.csv
> > RegionAB-19941018.csv
> > RegionAB-19941122.csv
> > RegionAB.csv
> >
> > The first file (file1)  should include all files that starts with
> 'RegionAB' and inlcude the following files
>
> cat RegionAB-*.csv RegionAB.csv > file1
>
>
> > The second output  file  (file2) should include all files that start
> with 'Region'
> >
> > Region-19940726.csv
> > Region-19940816.csv
> > Region-19940920.csv
> > Region-19941018.csv
> > Region-19941122.csv
> > Region.csv
>
> cat Region-*.csv Region.csv > file2
>
>
​Greg gave you the canonical answer. But, if you just want to read those
files and (1) you don't want to merge them together into a cumulative file
(perhaps due to space) and (2) your application is not written to handle
multiple separate files, I will mention "process substitution". In most
shells, you might need to do something like:

cat Region-*.csv Region.csv >tempfile.csv
some-program tempfile.csv
rm tempfile.csv

But with BASH, you can use process substitution:

some-program <(cat Region{,-*}.csv​)

Of course, the above only works if "some-program" only wants to _read_
those files, not update them.

​And, just to be complete, note that "Region{,-*}​.csv" expands into
"Region.csv" and "Region-*.csv" and then "Region-*.csv" expands into every
file which starts with "Region-" and ends with ".csv". I don't know how
many people use the {}  or "brace expansion". But I really like it for
three reasons (none really good): (1) I'm lazy and don't like to retype
stuff; (2) it "looks cool"; (3) it messes with other people's minds.


-- 
Heisenberg may have been here.

http://xkcd.com/1770/

Maranatha! <><
John McKown