Hello,
I have only recently discovered parallel and wish I had found it years
ago. Thanks for such a great tool, Ole! Mange tak!
I have a couple of questions from my reading of the tutorial ('man
parallel_tutorial').
$ parallel --version
GNU parallel 20150722
Q1.
Around line 420 there is this in the discussion of Perl expression
replacement strings:
If the short hand starts with '{' it can be used as a positional
> replacement string, too:
>
parallel --rpl '{..} s:\.[^.]+$::;s:\.[^.]+$::;' echo '{..}' :::
> foo.tar.gz
Positional replacement strings like {2} aren't introduced until the next
section. What is the advantage in using this replacement string as '{..}'
rather than '..' ?
(BTW, "short hand" as two words looks strange to me. I would write
"shorthand". As two words it implies an actual human hand that is shorter
than normal, at least to me!)
Q2.
Around line 1595 we have an example of records with multiple lines:
If a record is 75 lines -L can be used:
cat num1000000 | parallel --pipe -L75 wc
>
Output (the order may be different):
>
165600 165600 1048095
> 149850 149850 1048950
> 149775 149775 1048425
> 149775 149775 1048425
> 149850 149850 1048950
> 149775 149775 1048425
> 85350 85350 597450
> 25 25 176
We see that 6 processes got the default block of 1 MB or so, a seventh got
most of the remainder, and an eight got a tiny scrap. Why was there an
eighth process? In other words, why didn't the seventh process get all of
the rest? Is the reason simply that the seventh process stopped receiving
input with the end of the last full record, and the eighth got the partial
record that was left over?
- Rory Molinari
