The Linux Questions Thread: a bunch of pitfalls, but technically it's possible

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Linux Questions Thread: a bunch of pitfalls, but technically it's possible

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evol262: Nov 30, 2010; #!/usr/bin/perl

In the future, you should also dump stuff you compile yourself in /usr/local

Check whether either file is owned by a package (rpm -qf), though

# ? Mar 15, 2017 01:13

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# ? Jun 11, 2024 08:08

Robo Reagan: Feb 12, 2012; by Fluffdaddy

Is uGet still what I should be using for an IDM, or has something else come along?

# ? Mar 15, 2017 15:13

Xae: Jan 19, 2005

The final pieces of hardware for my home server arrived today.

I'm looking for a nice headless server that will mostly be just a file server. But I would also like to have the ability to run a little home lab for some development work.

Any reccomended distros? I'm wavering back and forth between Ubuntu and Debian. I've got a laptop and dual boot with Ubuntu but it's given me no end of problems.

# ? Mar 15, 2017 19:47

thebigcow: Jan 3, 2001; Bully!

Xae posted:

The final pieces of hardware for my home server arrived today.

I'm looking for a nice headless server that will mostly be just a file server. But I would also like to have the ability to run a little home lab for some development work.

Any reccomended distros? I'm wavering back and forth between Ubuntu and Debian. I've got a laptop and dual boot with Ubuntu but it's given me no end of problems.

FreeNAS 10 just came out with full support for the FreeBSD hypervisor. You could be an early adopter, entitled to all the joys that come with it.

# ? Mar 15, 2017 20:23

Xae: Jan 19, 2005

thebigcow posted:

FreeNAS 10 just came out with full support for the FreeBSD hypervisor. You could be an early adopter, entitled to all the joys that come with it.

How much of a pain in the rear end will it be if I want to run a local game server or two on the box?

I'm not sure what level of comparability FreeBSD and Linux have for that.

# ? Mar 15, 2017 20:38

anthonypants: May 6, 2007; by Nyc_Tattoo; Dinosaur Gum

Xae posted:

How much of a pain in the rear end will it be if I want to run a local game server or two on the box?

I'm not sure what level of comparability FreeBSD and Linux have for that.

I would imagine that a FreeBSD hypervisor would support a Linux guest virtual machine quite well.

# ? Mar 15, 2017 20:48

RFC2324: Jun 7, 2012; http 418

Xae posted:

The final pieces of hardware for my home server arrived today.

I'm looking for a nice headless server that will mostly be just a file server. But I would also like to have the ability to run a little home lab for some development work.

Any reccomended distros? I'm wavering back and forth between Ubuntu and Debian. I've got a laptop and dual boot with Ubuntu but it's given me no end of problems.

CentOS is pretty much the gold standard for a virtual host, from what I have seen. Run that, then just spin up VMs for whatever you want to do, with the best OS for it.

# ? Mar 15, 2017 21:16

Volguus: Mar 3, 2009

RFC2324 posted:

CentOS is pretty much the gold standard for a virtual host, from what I have seen. Run that, then just spin up VMs for whatever you want to do, with the best OS for it.

Why not go with ESXi? Wouldnt it have less overhead?

# ? Mar 15, 2017 21:20

Eletriarnation: Apr 6, 2005; People don't appreciate the substance of things...
objects in space.; Oven Wrangler

I figured by "will mostly be just a file server" that Xae wanted the base OS to do the fileserving and ESXi won't do that, but it's an option if you're OK with the fileserver being a VM.

# ? Mar 15, 2017 21:26

evol262: Nov 30, 2010; #!/usr/bin/perl

Volguus posted:

Why not go with ESXi? Wouldnt it have less overhead?

Not really, surprisingly. Density and CPU metrics are about neck and neck between KVM and vmkernel. The amount of services running/memory used on a clean centos install is virtually nil, and the ability to run services (like fileservers) directly on the host is a distinct advantage for "one box does it all" lab setups.

# ? Mar 15, 2017 21:49

waffle iron: Jan 16, 2004

evol262 posted:

In the future, you should also dump stuff you compile yourself in /usr/local

Check whether either file is owned by a package (rpm -qf), though

A lot of times I will install stuff I'm playing with in ~/.local because it's a directory that already exists.

# ? Mar 15, 2017 22:14

xzzy: Mar 5, 2009

~/t is my default test destination.

Or ~/u if ~/t already exists. And so on until I run out of letters. Usually I clean up the mess before I get to z.

# ? Mar 15, 2017 22:31

unruly: May 12, 2002; YES!!!

The XKCD Larper posted:

Thank you

https://my.mixtape.moe/qmmiwo.mov

Ha! For some reason this makes me extremely happy.

I'm glad I've given you the gift of the soundboard. Use it wisely (in extreme poor taste)!

# ? Mar 16, 2017 00:18

Paul MaudDib: May 3, 2006; TEAM NVIDIA:
FORUM POLICE

evol262 posted:

Not really, surprisingly. Density and CPU metrics are about neck and neck between KVM and vmkernel. The amount of services running/memory used on a clean centos install is virtually nil, and the ability to run services (like fileservers) directly on the host is a distinct advantage for "one box does it all" lab setups.

To quantify this, on Ubuntu Server you can easily bring up a basic system with ~64 MB of memory used on Ubuntu Server last time I checked, and I would imagine CentOS is similar.

# ? Mar 16, 2017 02:53

Xae: Jan 19, 2005

I ended up going with FreeNas 10.

The Interface is slick as hell and other than loving my initial install by putting all 3 HDs at the Boot Volume it has gone pretty well.

Looks like there is still some issues with the Docker Integration though. About half of the listed images fail to install saying they are missing the image.

For the moment it is doing its job of replacing my failing old Qnap appliance.

# ? Mar 16, 2017 04:37

Experto Crede: Aug 19, 2008; Keep on Truckin'

Is there anyway when you're building an SRPM file to specify the installation prefix for the package? (Basically I need an alternative version of an RPM that will install in /opt/foo as the top directory rather than /)

I tried setting the %_prefix macro in ~/.rpmmacros but this was the prefix for looking for libraries, etc. so that wasn't it.

So either setting a global prefix within the spec file or at least letting it be relocated so I can add the package with rpm --prefix would be great.

# ? Mar 16, 2017 17:46

evol262: Nov 30, 2010; #!/usr/bin/perl

Experto Crede posted:

Is there anyway when you're building an SRPM file to specify the installation prefix for the package? (Basically I need an alternative version of an RPM that will install in /opt/foo as the top directory rather than /)

I tried setting the %_prefix macro in ~/.rpmmacros but this was the prefix for looking for libraries, etc. so that wasn't it.

So either setting a global prefix within the spec file or at least letting it be relocated so I can add the package with rpm --prefix would be great.

Either use:

Prefix: /opt/foo

Or wedge ./configure in %build

# ? Mar 16, 2017 20:14

xzzy: Mar 5, 2009

Prefix is the superior option because it allows the rpm --prefix option to work.

The only part I don't like about it is the files section, you still have to specify the full path (like if you set prefix to /bar you still have to put /bar/etc/myconfig.conf in the files section). The build process isn't smart enough to build the path for you.

# ? Mar 16, 2017 20:22

Vulture Culture: Jul 14, 2003; I was never enjoying it. I only eat it for the nutrients.

I've got a kernel crash dump that I'm trying to debug with the kernel crash tool. Anyone know how to determine what area a specific address (in this case, the instruction pointer, pointing at a page marked NX) belongs to?

e: kmem -p only gives me this:

code:

crash> kmem -p ffff8823efcd6d00
      PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS
ffffea008fbf3580 23efcd6000                0        0  1 17fff8000000400 reserved

From what I remember of the Linux VM subsystem, reserved strongly suggests this is memory belonging to a driver (predictably). Any way for me to tell which one?

Vulture Culture fucked around with this message at 15:25 on Mar 17, 2017

# ? Mar 17, 2017 15:13

evol262: Nov 30, 2010; #!/usr/bin/perl

I mean, you look at `vm`, but that probably won't be useful with the reserved flag. `dev -i` will probably be equally useless. `vm -P 23efcd6000` might get you started, but if it is a driver, you'll end up in the dark spaces of `dis` eventually...

# ? Mar 17, 2017 16:12

anthonypants: May 6, 2007; by Nyc_Tattoo; Dinosaur Gum

I'm updating SSL certificates and I want to inspect the server certificates for our SFTP server. openssl s_client -starttls ftp -showcerts -servername sftp.domain.com -connect internalserver.domain.local:port doesn't display the certs. In fact, the only thing it shows is "CONNECTED(00000003)". Adding a -debug to the above command spits out what I'm assuming is cipher negotiation, but nothing related to the certs. What am I doing wrong?

e: Ah, sftp uses SSH keys. Good 2 know.

anthonypants fucked around with this message at 21:36 on Mar 17, 2017

# ? Mar 17, 2017 21:12

redeyes: Sep 14, 2002; by Fluffdaddy

Not sure if this is a good thread to ask. I want a GUI/desktop that allows pinning folders and shortcuts. I'd really love something that had system desktop icons, kind of like Macs. I've tried looking around for the past few weeks and really came up blank other than windows or mac clone type desktops. Is there a modern thing for me to check out? I am a novice pretty much.

# ? Mar 18, 2017 02:43

RFC2324: Jun 7, 2012; http 418

redeyes posted:

Not sure if this is a good thread to ask. I want a GUI/desktop that allows pinning folders and shortcuts. I'd really love something that had system desktop icons, kind of like Macs. I've tried looking around for the past few weeks and really came up blank other than windows or mac clone type desktops. Is there a modern thing for me to check out? I am a novice pretty much.

Pretty sure you can do all that with KDE, unless I am not understanding what you want.

Can't imagine you haven't run across KDE yet tho

# ? Mar 18, 2017 02:57

Wicaeed: Feb 8, 2005

I've spent the last week pounding my head into the wall troubleshooting this issue and have made 0 progress. Help!.

I've got two similar hosts in an environment separated by an ocean that serve as a backup repository for DB backups. I'm using a script which calls the inotifywait program to fire off an aws cli command to upload today's backups into an S3 bucket.

The US side works fine (VM's on VMware), but I'm having all kinds of issues with our EU side, which is hosted by AWS.

My clients are mounting the folder remotely with SSHFS with a backup user, which has the same id across all systems.

While strace'ing the inotifywait process, it gets an error when the client saves a file/folder structure into a watched directory:

code:

root@a:/srv/db_backups/postgresql# strace -p 24415
Process 24415 attached
select(4, [3], NULL, NULL, NULL)        = 1 (in [3])
ioctl(3, FIONREAD, [16])                = 0
read(3, "\2\0\0\0\0\200\0\0\0\0\0\0\0\0\0\0", 65536) = 16
select(4, [3], NULL, NULL, NULL
')        = 1 (in [3])
ioctl(3, FIONREAD, [32])                = 0
read(3, "\7\0\0\0\0\1\0@\0\0\0\0\20\0\0\00020170318\0\0\0\0\0\0\0\0", 65536) = 32
lstat("/srv/db_backups/postgresql/<hostname>/dumps/20170318", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0
openat(AT_FDCWD, "/srv/db_backups/postgresql/<hostname>/dumps/20170318", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = -1 EACCES (Permission denied)
sendto(4, "<30>Mar 18 01:02:39 inotifywait["..., 151, MSG_NOSIGNAL, NULL, 0) = 151
select(4, [3], NULL, NULL, NULL

A successful call looks like this snippet:

code:

read(3, "\10\0\0\0\0\1\0@\0\0\0\0\20\0\0\00020170319\0\0\0\0\0\0\0\0", 65536) = 32
lstat("/srv/db_backups/postgresql/<hostname>/dumps/20170319", {st_mode=S_IFDIR|0775, st_size=4096, ...}) = 0
openat(AT_FDCWD, "/srv/db_backups/postgresql/<hostname>/dumps/20170319", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 5

Clearly it's a permission denied error, but WHY?

Both servers have SSHFS installed and mounted in fstab with the following:

code:

<user>@<hostname>:/srv/db_backups /archive/network fuse.sshfs delay_connect,user,identityfile=/var/lib/postgresql/.ssh/id_rsa,allow_other,uid=34,gid=34,_netdev 0 0

All backups save into a directory under the path /srv/db_backups/postgresql/<servername> that looks like the following from the clients(hostnames omitted):

code:

drwxrwxr-x 8 backup backup 4.0K Mar 17 01:05 .
drwxrwxr-x 3 backup backup 4.0K Sep 29 23:21 ..
drwxrwxr-x 3 backup backup 4.0K Mar 17 01:16 <hostname>
drwxrwxr-x 3 backup backup 4.0K Mar 16 00:06 <hostname>
drwxrwxr-x 3 backup backup 4.0K Sep 30 00:00 <hostname>
drwxrwxr-x 3 backup backup 4.0K Sep 30 00:00 <hostname>
drwxrwxr-x 3 backup backup 4.0K Jan 30 19:14 <hostname>
drwxrwxr-x 3 backup backup 4.0K Sep 29 23:20 <hostname>

And this from the server:

code:

root@a:/srv/db_backups/postgresql/<hostname># tree -pgu
.
&#9492;&#9472;&#9472; [drwxrwxr-x postgres postgres]  dumps
    &#9500;&#9472;&#9472; [drwxrwxr-x postgres postgres]  20170201
    &#9474;�� &#9500;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  globals.sql
    &#9474;�� &#9492;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  dump.gz
    &#9500;&#9472;&#9472; [drwxrwxr-x postgres postgres]  20170301
    &#9474;�� &#9500;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  globals.sql
    &#9474;�� &#9492;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  dump.gz
    &#9500;&#9472;&#9472; [drwxrwxr-x postgres postgres]  20170306
    &#9474;�� &#9500;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  globals.sql
    &#9474;�� &#9492;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  dump.gz
    &#9500;&#9472;&#9472; [drwxrwxr-x postgres postgres]  20170313
    &#9474;�� &#9500;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  globals.sql
    &#9474;�� &#9492;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  dump.gz
    &#9500;&#9472;&#9472; [drwxrwxr-x postgres postgres]  20170317
    &#9474;�� &#9500;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  globals.sql
    &#9474;�� &#9492;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  dump.gz
    &#9500;&#9472;&#9472; [drwxrwxr-x postgres postgres]  20170318
    &#9474;�� &#9500;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  globals.sql
    &#9474;�� &#9492;&#9472;&#9472; [-rw-rw-r-- postgres postgres]  dump.gz

if I run inotifywait with sudo everything functions fine. My user is in the backup group, and has no problems reading/writing/deleting these files.

Any ideas?

# ? Mar 18, 2017 03:11

taqueso: Mar 8, 2004

redeyes posted:

Not sure if this is a good thread to ask. I want a GUI/desktop that allows pinning folders and shortcuts. I'd really love something that had system desktop icons, kind of like Macs. I've tried looking around for the past few weeks and really came up blank other than windows or mac clone type desktops. Is there a modern thing for me to check out? I am a novice pretty much.

I believe you can do that in gnome but you have to enable it with gnome-tweak-tool.

# ? Mar 18, 2017 03:27

seance snacks: Mar 30, 2007

edit: moved

seance snacks fucked around with this message at 16:57 on Mar 18, 2017

# ? Mar 18, 2017 07:03

SeaborneClink: Aug 27, 2010; MAWP... MAWP!

I need to give someone (remote) a Linux primer/kickstart over 3 months. Does anyone know of any interactive labs from the perspective of 'managing remote hosts via ssh' that basically covers from the ground up "Here's ls; it shows you things, here's cd; it's how you move around. Here's an overview of these stupid 3 numbers and how they dictate what you can & cannot do."

Any recommendations for open courseware, interactive shell tutorials or video series are greatly appreciated. To be explicitly clear I do not want a "Install Ubuntu on your computer in 5 easy steps" or really, any time of local Linux setup guide, type of experience and don't have time to explain "/var/log/ is where to look first when things break" type of thing. Paid is fine, free is better :cheers:

# ? Mar 19, 2017 05:35

Tigren: Oct 3, 2003

SeaborneClink posted:

I need to give someone (remote) a Linux primer/kickstart over 3 months. Does anyone know of any interactive labs from the perspective of 'managing remote hosts via ssh' that basically covers from the ground up "Here's ls; it shows you things, here's cd; it's how you move around. Here's an overview of these stupid 3 numbers and how they dictate what you can & cannot do."

Any recommendations for open courseware, interactive shell tutorials or video series are greatly appreciated. To be explicitly clear I do not want a "Install Ubuntu on your computer in 5 easy steps" or really, any time of local Linux setup guide, type of experience and don't have time to explain "/var/log/ is where to look first when things break" type of thing. Paid is fine, free is better

I've heard great things about Linux Academy, but I've never used it myself. I think Codeacademy has a Linux basics course too.

This one seems like a good command line introduction.

https://linuxacademy.com/linux/training/course/name/mastering-the-linux-command-line

Tigren fucked around with this message at 05:48 on Mar 19, 2017

# ? Mar 19, 2017 05:37

anthonypants: May 6, 2007; by Nyc_Tattoo; Dinosaur Gum

SeaborneClink posted:

I need to give someone (remote) a Linux primer/kickstart over 3 months. Does anyone know of any interactive labs from the perspective of 'managing remote hosts via ssh' that basically covers from the ground up "Here's ls; it shows you things, here's cd; it's how you move around. Here's an overview of these stupid 3 numbers and how they dictate what you can & cannot do."

Any recommendations for open courseware, interactive shell tutorials or video series are greatly appreciated. To be explicitly clear I do not want a "Install Ubuntu on your computer in 5 easy steps" or really, any time of local Linux setup guide, type of experience and don't have time to explain "/var/log/ is where to look first when things break" type of thing. Paid is fine, free is better

What is their level of familiarity of the command line?

# ? Mar 19, 2017 05:40

SeaborneClink: Aug 27, 2010; MAWP... MAWP!

anthonypants posted:

What is their level of familiarity of the command line?

Let's say, about zero. I'm looking for a literal crash course in the most basically explained way possible. Think Jeremy from CBT Nuggets.

# ? Mar 19, 2017 05:48

Ashex: Jun 25, 2007; These pipes are cleeeean!!!

Anyone know the right way to set stripe cache size at boot? I created a timer that fires the following at boot:

quote:

[Unit]
Description=mdadm array options

[Service]
ExecStart=/usr/bin/echo 16384 > /sys/block/md0/md/stripe_cache_size

[Install]
WantedBy=multi-user.target

But I just checked the size and it came back as 256.

# ? Mar 19, 2017 12:37

Vulture Culture: Jul 14, 2003; I was never enjoying it. I only eat it for the nutrients.

Ashex posted:

Anyone know the right way to set stripe cache size at boot? I created a timer that fires the following at boot:

But I just checked the size and it came back as 256.

That's not a valid thing to put in ExecStart -- that command isn't run in a shell, so you're literally echoing those three arguments (check journalctl to verify). Try /bin/sh -c 'echo 16384 > /sys/block/md0/md/stripe_cache_size'

e: the right way is probably something in mdadm.conf but I'm bad at Linux so

# ? Mar 19, 2017 17:49

hifi: Jul 25, 2012

Some distributions (ubuntu for sure, maybe debian, not RHEL-likes) give you a /etc/sysfs.conf file when you install sysfsutils that will do what you want

# ? Mar 19, 2017 17:51

evol262: Nov 30, 2010; #!/usr/bin/perl

Or you can set a sysctl, which works everywhere

# ? Mar 19, 2017 20:11

Ashex: Jun 25, 2007; These pipes are cleeeean!!!

Vulture Culture posted:

That's not a valid thing to put in ExecStart -- that command isn't run in a shell, so you're literally echoing those three arguments (check journalctl to verify). Try /bin/sh -c 'echo 16384 > /sys/block/md0/md/stripe_cache_size'

e: the right way is probably something in mdadm.conf but I'm bad at Linux so

Thanks for the tip, I adjusted the service file and will see what happens.

hifi posted:

Some distributions (ubuntu for sure, maybe debian, not RHEL-likes) give you a /etc/sysfs.conf file when you install sysfsutils that will do what you want

I'm running Fedora Core and sysfsutils only provides systool that doesn't provide write capabilities.

evol262 posted:

Or you can set a sysctl, which works everywhere

Do you have an example? I checked available attributes with "sysctl -aN" and there's nothing setting stripe cache size (nor is anything available for md0).

# ? Mar 20, 2017 09:55

Vulture Culture: Jul 14, 2003; I was never enjoying it. I only eat it for the nutrients.

Ashex posted:

I'm running Fedora Core and sysfsutils only provides systool that doesn't provide write capabilities.

Look into tuned.

evol262 posted:

Or you can set a sysctl, which works everywhere

Don't sysctls map to /proc/sys, not sysfs?

# ? Mar 20, 2017 14:35

evol262: Nov 30, 2010; #!/usr/bin/perl

Ashex posted:

Do you have an example? I checked available attributes with "sysctl -aN" and there's nothing setting stripe cache size (nor is anything available for md0).

Vulture Culture posted:

Don't sysctls map to /proc/sys, not sysfs?

Yes. I skimmed/replied too fast, and missed the fact there was no leading /proc...

# ? Mar 20, 2017 15:19

R3DW0LF: Apr 4, 2016

Tigren posted:

I've heard great things about Linux Academy, but I've never used it myself. I think Codeacademy has a Linux basics course too.

This one seems like a good command line introduction.

https://linuxacademy.com/linux/training/course/name/mastering-the-linux-command-line

I've used linux academy, their courses got me my certifications, definitely recommend.

# ? Mar 20, 2017 16:52

DOA: Nov 17, 2016

I switched to linux about 6 months ago and sometimes when im gonna install something it says like "Error: This package is uninstallable Dependency is not satisfiable" so i think thats ok i just install the dependency missing, but then that dependency need even more dependencies and so on, and i end up using 1 hour to install something (most stuff are easy to install but i go crazy sometimes because of this)

maybe its because i have been using windows for over 20 years and dont understand much about linux yet, but sometimes installing stuff seems like a real hassle, also there are so many distros with some differences it can be hard to search for solutions that works for mine

# ? Mar 21, 2017 02:03

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# ? Jun 11, 2024 08:08

anthonypants: May 6, 2007; by Nyc_Tattoo; Dinosaur Gum

DOA posted:

I switched to linux about 6 months ago and sometimes when im gonna install something it says like "Error: This package is uninstallable Dependency is not satisfiable" so i think thats ok i just install the dependency missing, but then that dependency need even more dependencies and so on, and i end up using 1 hour to install something (most stuff are easy to install but i go crazy sometimes because of this)

maybe its because i have been using windows for over 20 years and dont understand much about linux yet, but sometimes installing stuff seems like a real hassle, also there are so many distros with some differences it can be hard to search for solutions that works for mine

Which distro?

# ? Mar 21, 2017 02:15

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Linux Questions Thread: a bunch of pitfalls, but technically it's possible

«‹›1040 »