DevHeads.net

Postings by Kevin O'Gorman

How to do a bulk download of password-protected data?

I've had to do this manually many times. If it weren't for the
password-protection, it would be easy with wget or rsync. As it is, I have
to log in to whatever site contains the data with my web browser, then
click on each and every one of what is sometimes over one hundred different
links.

I understand that wget has some capability of sending cookies, and that
that's how password-related credentials are presented, but I do not know
how to set it up. Are there any howto's youtubes, or the like about this?

++ kevin

How does MySQL really start?

It was suggested here that the script /etc/init.d/mysql is used in starting
MySQL but I have
been unable to confirm that by injecting code into it.

How to start and stop mysql?

I need to start and stop mysql, and I've only figured out how to stop it.
I need to start it (not rebooting) so that I can temporarily use different
options. In my case, I need --skip-grant-tables.

How to coordinate the clock when dual-booting with Windows

I've installed Ubuntu into a Windows laptop. I missed the place where I
was supposed to tell the install that the clock will be kept in local time,
so switching between Linux and Windows is a pain.

Is there a way to fix this short of going back and doing it again?

Name resolution with unqualified names

First an admission: I have only a general understanding of IP and name
resolution.

My issue has to do with my local subnet, so let me describe it:
1. there's a fairly new LinkSys AC1900 MU-MIMO gigabity router connected to
my cable modem. Most of the things attached to it have reserved IP numbers
in the 10.x.x.x range.

2. Since I have more than 4 wired connections, I have 2 TP-LINK TP-SG105E
switches, one in my garage (where my 4 desktop computers live), one in my
office where there are also a printer, 2 laptops and some other stuff.

3.

Can I avoid apt?

I see that apt-get has been replaced by apt, sort of.

I don't like apt. I'm in the habit of doing my updates under the script(1)
command and that banner that apt puts at the bottom of the screen makes the
files unreadable.

Is there a way to disable it? Possibly by lying to apt about my terminal's
capabilities?

++ kevin

Ubuntu server holding back on me

I've just started using Ubuntu Server on a couple of extra machines.

Machine check exception, but what kind?

I've been having trouble with two of my personal computers. One is from
System76 and their great support staff suggested I load package mcelog to
monitor for machine check exceptions (MCE). Sounded good to me, so I did
it on all my Ubuntu machines (I have 4 if you count laptops).

Lo and behold, one of the other machines glitched last night. Not the
System76 one, but a home-brew I built myself (with a little help from my
friends). It's got a medium-fast Core i-7 on an ASUS board.

What is "Disks" really

I'm a newb on Ubuntu proper (I mostly use Xubuntu), but have recently
acquired a machine from
System76, and the warranty only works if I keep it under Ubuntu. So I do.

Working on a current problem, they have me running the program Disks from
the 16.04.2 distro on a USB stick. That is I enter "Disks" on the Dash,
and get a pretty neat diagnostic tool.

Thing is, I can't figure out what program I'm actually running. I'd like
to access it, or get it, on my Xubuntu systems.

Help, my RAID won't start

I've been fooling with this for a while. Some things are fixed, but the
darned thing still isn't right.

I've been following advice from a combination of sources, because nothing
I've found is complete, but that makes it harder to be sure I'm on the
right track.

So here it is: a core i-7, 32GB RAM, 6 internal hard drives, 4 of which are
4 TB. Three of those four are for my RAID, which I want to set up as
RAID5.

Block size for large filesystems

I've been using gparted for creating and managing filesystems for so long I
didn't really think about it too much. But now that I'm fooling around
with RAID, I've bumped into soemthing I maybe should have been paying
attention to all along.

It's the block size. Gparted does not seem to have an option to set the
block size when it formats a new partition. It just used 512B blocks. I'm
seeing recommendations for 4 KB blocks on large filesystems, and most of
mine are 32GB, and I have two that are 7TB and 11TB RAID arrays
respectively.

Does anybody know how much of a difference this makes?

Trouble building a RAID 4 array with mdadm

I'm on Xubuntu 16.04.2 LTS, using mdadm. I've already built a RAID-1 array
and had some success with it.

Question about a mismatch between documentation and how mdadm currently works.

I'm fooling around with RAID on Linux for the first time. Lots to learn.
I have one issue that
keeps coming up with creating RAID arrays with mdadm.

The documentation I have all says to create arrays with something like
mdadm --create /dev/md0 (and some more stuff)
and what follows really does indicate they expect the array to appear as
/dev/md0. What
happens when I try it is that the array is created as /dev/md127.

Help, my disk array has one dead member

I need a quick bit of advice.

I have a stripe array under mdadm, and one of the disks is dead or dying.
Nevertheless, there's a bunch of stuff that is NOT gone, and I'd like to
capture all I can before I even power this thing off.
I'm missing some inodes, as well as some file and directory blocks.

It's all hobby stuff, and it's all rebuildable, but I'd like to capture all
the clues I can.

I'm looking for a way to copy the whole directory structure, just omitting
any file or directory that reports an error in the process.

Bash cannot fork? How odd.

I have run into a very peculiar thing. I was monitoring processes on a
Xeon I recently bought, and overnight the monitoring stopped working. It
was just a Bash script in a loop, running once per minute, and after a
while it stopped functioning normally.

REISUB -- now what?

I've got a big machine running Ubuntu that's I'd prefer kept running all
the time. I don't always get what I want, of course...

Today, for the second time in about three weeks, it completely froze.
Fortunately, I kept a printed copy of
<a href="http://blog.kember.net/articles/reisub-the-gentle-linux-restart/" title="http://blog.kember.net/articles/reisub-the-gentle-linux-restart/">http://blog.kember.net/articles/reisub-the-gentle-linux-restart/</a> in a
folder with assorted HOWTO-type articles, and was able to restart it that
way.

Odd need: to track down NUL bytes

I've never run into this before, despite running Unix or Linux in my home
continuously since about 1986. I had a system freeze-up on Jan 31 from
unknown causes. The system affected is run as a computing server for a
hobby project of mine. I thought all was well, and that I was able to
salvage the partial outputs of the jobs that were running. I was wrong.

I now discover that some files that were under construction at that time
are corrupted with extensive NUL bytes. These are usually text files. I
want to find all such files and "cleanse" them to recover what information
I can.

Problems installing grub

I'm having problems... and because I'm doing something a bit tricky, I'm
probably confused.

I have to send my motherboard in for a warranty repair, and don't want my
system out of service longer than an hour or so. I have to send the HDD in
with it because of the kind of problem I'm having ("stability"). So I've
made a clone of all of the partitions on another drive and I'm trying to
make it work. It's not going well.

Several things are bothering me, but I'll just describe the first one.

Behavior change #2 in Synaptic

I was reminded by another post here that there's been a change that
bothered me when I went from 14.04 LTS to 16.04.

I seem to remember that if I was displaying, for instance, installed
packages, then if I further did a search, the search applied only to those
installed packages, not the entire universe. As things now stand, my
search results are often so numerous that it's very hard to locate the
things I'm really interested in.

Which OpenGL package to install?

I just posted this with a different subject, but immediately realized I
needed one that mentioned OpenGL. Sorry for the repetition.

I'm trying to get Qt Creator working for a hobby project, so I downloaded
it.

Qt Creator not set up properly

I'm trying to get Qt Creator working for a hobby project, so I downloaded
it. I'm trying to work through a tutorial, and getting a failure at the
first compile.

There's a screenshot at <a href="https://goo.gl/photos/efcPqS3UshvDL1Fu7" title="https://goo.gl/photos/efcPqS3UshvDL1Fu7">https://goo.gl/photos/efcPqS3UshvDL1Fu7</a>

Apparently, I need some OpenGL stuff, but I know nothing about OpenGL, and
can't make much sense of the package names that might relate to it.

For starters, does anybody know if there's a package that would satisfy a
reference to a C or C++
#include <GL/gl.h> ???

Is there no python3-scipy documentation package?

I'm looking to use scipy in python3, and find that unlike python2, there is
no obvious documentation package for python3. At least not when I do a
search in synaptic.

What i do find is

python-scipy
python-scipy-doc

python3-scipy

Any web authors using Python out there? I need advice.

I have a web site I wrote in the '90s as a hobby project, before I ever
heard the word "framework" in reference to the web, before I heard of
SQLite, and while learning Python. It needs work. It shows the outcomes
of some known games of Hex. See it at <a href="http://hex.kosmanor.com/hex-bin/board" title="http://hex.kosmanor.com/hex-bin/board">http://hex.kosmanor.com/hex-bin/board</a>
.

The Python code is run as CGI scripting, which I gather is old technology,
and is certainly slow. I'd like to do better. It would make sense to stay
with Python, but it's not essential. The database is my own C code wrapper
around gdbm, as a Python module.

Some help with Ubuntu

It has been a while since I used Ubuntu proper, having switched to Xubuntu
as soon as Unity came on the scene. But I just got a new system from
System76, and I don't want to fool with it too much until I know what I'm
doing a bit better. So I'm having some issues with the user interface.
Usually a web search gets me an answer, but I'm worried about this one:

From time to time, doing different things, the whole thing seems to
freeze. No response to the keyboard, even things like CTRL-C,
CTRL-ALT-function key, three-finger-salute and so on. No response to the
mouse. Nothing.

Odd error report from grub-install

I just submitted a bug about this, but it occurs to me you list users may
have seen this before, or have suggestions.

I have just now removed some old kernels. I did an update-grub, but
grub-install /dev/sda
is reporting an odd error that I've never seen before:

root@roisin:~# grub-install /dev/sda
Installing for i386-pc platform.
grub-install: warning: Sector 50 is already in use by the program
`FlexNet'; avoiding it. This software may cause boot or other problems in
future. Please ask its authors not to store data in the boot track.

I do not know what FlexNet is.

Update check is failing

I have a big red "!" icon in my top panel (on Xubuntu), and a message that
reads "The update information is outdated. This may be caused by network
problems or by a repository that is no longer available.

Sound stopped working on both 14.04 and 15.04

I have a laptop running Xubuntu 15.04 and a desktop running 14.04. Once in
a while, I don my earbuds to listen to something. It used to work, but no
longer does on either machine when running these distros. Booting into
Windows (resp Win 10 and Win 7) sound works, so I don't suspect any
hardware failure.

Doing the lowest-level test I know how to do, I used mpg123 to turn an .mp3
into a .wav, and tried to play it with aplay. It reports it's working, but
no sound comes out. I've fooled with volume controls and such to no
avail.

How to do a release upgrade (example: 14.10 -> 15.04) on the command-line

Every time I do this, something needs fixing. Accordingly, I'd like to get
a log of all of the actions, outputs and versions involved in doing the
upgrade from utopic to vivid. I'm most comfortable on the command line for
such tasks, but a quick look at the man pages that I know does not tell me
how to do this.

Anybody got a clue for me?

Help with sound

I've had no sound with Xubuntu on this system since I switched to HDMI
monitors. This has been true on two different motherboards. I suspect
it's because the HDMI monitors do NOT support sound, but the HDMI interface
does. I do not find sound controls on these monitors, or menu options
about sound.

The current motherboard has a built-in sound system as well, I have
attached speakers, and when I dual-boot to Windows 7, that's what it uses
and sound works just fine.

Help with DVD writing.

I'm running xubuntu 14.04 LTS, and just replaced my mobo. Now I cannot use
my DVD drive to burn a disk.

I'm using xfburn, or trying to. When I start it from the menu, nothing
happens. When I start it on the command line, I usually get

root@treat:~# xfburn
** Message: Using UDEV
^C

and it hangs forever, until I ^C it. One time it went on to change its
mind after a bit, and say it was using gstreamer transcoder, but things got
hung up soon after.

I also have a fresh install of 14.04.2, which does the same.

The drive itself is functional: Windows 7 burns disks just fine.

Any ideas?