On 1/11/17, Roman Fleysher <roman.fleys...@einstein.yu.edu> wrote:
> Dear SQLites,
>
> I am using exclusively sqlite3 shell for all the processing and may need
> ability to run bash commands and assign result to a column. For example:
>
> UPDATE result SET nRows =` wc -l fileNames` ;
>
> Here I used `` as would be in bash for command substitution. This would run
> wc command (word count), count number of lines in each file listed in column
> fileNames and update the row correspondingly.
>
> As far as I understand I should be able to write loadable extension to
> accomplish this.
No, You cannot do exactly what you describe with a loadable extension.
But you could, perhaps, create a loadable extension that implements a
new system() SQL function like this:
UPDATE result SET nRows = system('wc -l ' || fileNames);
Note that || is the SQL string concatenation operator. You didn't
say, but I'm guessing that fileNames is a column in the result table.
--
D. Richard Hipp
d...@sqlite.org
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