regex – The regular expression of GNU Octave may incorrectly number optional groups

Referral groups (parentheses) in a regular expression are executed with $1 $2 $3etc. in GNU Octave and matlab,

But in both GNU Octave and matlab Optional groups are not numbered if they do not match. Is this a bug?

Here is an example:

ans = c,b,a
ans = ,c,a

expected result of the second variant:


here is something similar in sed:

echo -e "abcnac" | sed -E 's/(a)(b)?(c)/3,2,1/'

If I look at the regular expression, there are three sets of parentheses, and the third is definitely the one that should match c so that c should come first in the output. However, since the second does not match, c is updated in the backreferences on slot 2.

I think that this is a mistake because the author of the regular expression may not know if a string will contain the optional bit or not. Regardless, the author must decide in advance what to replace by what reference.

It seems to me that sed If you do it correctly, the numbering should match the parentheses in the regular expression, not the way the groups match.

A workaround I'm using now is to be used * Quantifier and ? within the group, instead of making groups optional.

In order to:

ans = c,,a

However, this is more complicated with more complex regular expressions, e.g. For example, when searching for a variable with possibly an index:


should fit lambda and lambda(1)but also catches lamda() versus


That's what I really want, but that'll mess up the referencing.

I tested it very fast in Matlab and it seemed to be the same.

Gnu host – first impression

Proven Gnu Host Reseller Hosting for (only) 2 months. Need custom reseller hosting (more resources per cpanel) and you were one of the few people who wanted to get involved.

It is a relatively new and not very well-known hosting provider. Mention it so – for what it's worth (rather a first impression than a rating based on short-term usage):

Good availability, performance and very good customer service.

Does anyone have any experience with them?

Licensing – Does using a GNU Affero license pack in a large app mean that the entire app must be GNU?

I can not figure out if GNU Affero applies only to changes made to the GNU Affero license software or to ALL software that affects ANY GNU Affero software.

For example: I have a SaaS app where I have a server-side capability that responds to customer input and alters customer input using a GNU Affero license package.

by gnuPackage import gnu

def myFunction (x):
x = x + 1
x = gnu (x)
return x

So myFunctionI've written invokes a GNU Affero-licensed feature. Does that mean I have to let go? myFunction for the public under a GNU license? Or I would just give the code for give / give gnuPackage?

I'd like to use a GNU Affero license pack in my app, but I do not want to make my entire application, including what I've written, public.

grub2 – GNU Grub is displayed at boot time

After I reinstalled Lubuntu and downloaded the updates, I restarted it. When you turn on the system, GNU Grub 2.02 will be displayed. How can I fix it?

It may look like this (move the mouse below to see the text):

GNU GRUB version 2.02-2ubuntu8.13

Minimal BASH-like line editing is supported. For the first word, TAB lists possible command statements. Everywhere else TAB lists possible device or file completions.


Linux – problem with downloading files with GNU wget

I am a beginner in using this tool. So I have a mistake.

When I use GNU wget to download a PHP file from a directory that I can access, it contains PHP files. So I could download one, but the file contains no data. The weight of the file is 0 KB / s
When I access the directory through a browser, all .php files are displayed. I'm trying to access a specific file, but it's not showing me anything.

Answer 1.-: My idea of ​​why this happened was due to a limitation of the browser to visualize the information or the like.

The page that displays all the files indicates that all of these files contain data because their weight is 4.5 kbps. 5 Oh 4.3, all in weight kb / s.
However, when the command is executed, the content is empty.

Command used:

Wget ""



Is there a way to change the command I'm using to download the contents of this file?

Thank you for your attention and thank you for reading my question. Many thanks for the support.

Date – Time differences between Debian GNU and Linux

I'm trying to find out why my Linux has this time difference:

cmd1: date

out1: Sun 14 Jul 2019 00:45:59 CDT

cmd2: hwclock

out2: 2019-07-14 00: 46: 48.389904-04: 00

cmd3: timedatectl

out 3:

Local time: Sun 2019-07-14 01:47:17 -03 [correct time!]

World Time: Sun 2019-07-14 04:47:17 UTC

RTC Time: Sun 2019-07-14 04:47:17

Time Zone: America / Montevideo (-03, -0300)

System clock synchronized: yes

NTP service: active

RTC in local TZ: no

I have used Debian Strech with Awesome WM with the same problem now in Debian Buster with i3 … the same problem.

Help please!


bash – Gnu in parallel: How do I create a command with the –link option to extend the positional arguments?

The problem

I use GNU in parallel and want to pass two files to a program ::: Operator. My directory tree looks like this:

$ ls


The following code:

#! bin / bash
ones = $ (find SRR * pass * 1 * .fq)
Deuces = $ (Find SRR * pass * 2 * .fq)
Parallel link echo ::: $ ones ::: $ twos


SRR6301033_pass_1_trimmed.fq SRR6301033_pass_2_trimmed.fq
SRR6301034_pass_1_trimmed.fq SRR6301034_pass_2_trimmed.fq

But I need the output to look like this:

-1 SRR6301033_pass_1_trimmed.fq -2 SRR6301033_pass_2_trimmed.fq
-1 SRR6301034_pass_1_trimmed.fq -2 SRR6301034_pass_2_trimmed.fq

What I have already tried


$ parallel --link echo -1 ::: $ ones -2 ::: $ twos


-1 SRR6301033_pass_1_trimmed.fq SRR6301033_pass_2_trimmed.fq
-1 SRR6301034_pass_1_trimmed.fq SRR6301034_pass_2_trimmed.fq

and the:

$ parallel --link echo -1 ::: $ ones ::: $ twos


-1 SRR6301033_pass_1_trimmed.fq -2
-1 SRR6301034_pass_1_trimmed.fq SRR6301033_pass_2_trimmed.fq
-1 SRR6301037_pass_1_trimmed.fq SRR6301034_pass_2_trimmed.fq

motorola moto g – Can I install GNU / Linux in text mode on Android?

I want to use my old smartphone (Moto 3G) like Rassbery Pi to do some low-level stuff with just one terminal. I want to install GNU / Linux in text mode, access it with SSH, connect to the Internet, and have the option of entering the installed system with an on-screen keyboard, such as in Android.

Importantly, I want to completely remove android and install GNU / Linux at this point. I do not care about SMS, phone calls, etc. (But things like camera handling and the ability to see battery status, play / record sounds, or change screen brightness are nice).

Is there a distribution that can satisfy me? And how can I install the chosen system instead of Android?

boot – The GNU GRUB screen no longer loads Ubuntu OS

I worked well with Ubuntu, but one day, when I restarted it, it froze the Lap return to the GNU GRUB screen (the purple one), where there are only 3 options: Ubuntu / Advanced option for Ubuntu / System -Set up.
When I press Ubuntu, the screen freezes on the purple screen like it's being charged, but it can stay like that for hours.
I did not create a backup. What are the commands to restore my data?