new virtiofs filesystem – a FUSE based implementation for sharing physical host filesystems with virtual machine guests.
exFAT and sdFAT implementations – although my issues on Linux laptop are more to do with card reader than the exFAT filesystem on the microSD Cards
booting from CIFS (Wndows share) – don’t quite know how it works, but sounds too cool not to try!
lockdown module – a feature aimed to minimise access to Linux kernel even for root user – meaning no direct access to memory and device ports, limited calls and fully controlled debugfs amd kprobes.
Lots of new graphics cards are added into both AMD and Intel drivers, will be interesting to see if anything is improved for my Ubuntu 19.10 laptop.
Super quick advice today, but one of them pearls of experience that now and then saves your day. Learn how to check and confirm your recent changes to SSH daemon config file (/etc/ssh/sshd_config) won’t break your remote SSH access.
Why Double-Checking Configs Is A Good Idea
I should probably start a special section of Unix Tutorial someday, just to talk about how and when things can go wrong. These things below would certainly belong to that section.
Why it’s a good idea to check that your new config file is error free:
avoid getting service outage (syntax error means service won’t restart)
prevent service malfunction (if you end up with only partial service functionality)
don’t get yourself locked out of service (or server, in case of broken SSH)
Needed to reboot my Red Hat Enterprise Linux 8 desktop anyway, so decided to upgrade it to RHEL 8.1.
Check That Your Software Subscription is Active
For example, I realised that I have still been using the RHEL 8 beta subscription instead of the Developers License. After completing Red Hat subscription registration, I got the following:
greys@redhat:~ $ sudo subscription-manager list +-------------------------------------------+ Installed Product Status +-------------------------------------------+ Product Name: Red Hat Enterprise Linux for x86_64 Product ID: 479 Version: 8.1 Arch: x86_64 Status: Subscribed Status Details: Starts: 14/11/19 Ends: 13/11/20
Upgrade Red Hat OS with yum-update
yum tools are more integrated that many people though! So I’m still using yum update instead of dnf:
root@redhat:~ # yum update
Updating Subscription Management repositories.
Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs) 2.6 kB/s | 4.5 kB 00:01
Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs) 3.0 MB/s | 13 MB 00:04
Red Hat Enterprise Linux 8 for x86_64 - BaseOS (RPMs) 2.4 kB/s | 4.1 kB 00:01
Red Hat Enterprise Linux 8 for x86_64 - BaseOS (RPMs) 2.4 MB/s | 12 MB 00:04
Last metadata expiration check: 0:00:01 ago on Thu 14 Nov 2019 21:28:59 GMT.
Dependencies resolved.
Package Arch Version Repository Size
Installing:
yum-utils noarch 4.0.8-3.el8 rhel-8-for-x86_64-baseos-rpms 64 k
replacing dnf-utils.noarch 4.0.2.2-3.el8
kernel-debug-devel x86_64 4.18.0-147.0.3.el8_1 rhel-8-for-x86_64-baseos-rpms 14 M
kernel-devel x86_64 4.18.0-147.0.3.el8_1 rhel-8-for-x86_64-baseos-rpms 13 M
kernel-core x86_64 4.18.0-147.0.3.el8_1 rhel-8-for-x86_64-baseos-rpms 25 M
kernel x86_64 4.18.0-147.0.3.el8_1 rhel-8-for-x86_64-baseos-rpms 1.5 M
kernel-modules x86_64 4.18.0-147.0.3.el8_1 rhel-8-for-x86_64-baseos-rpms 22 M
Upgrading:
netcf-libs x86_64 0.2.8-12.module+el8.1.0+4066+0f1aadab rhel-8-for-x86_64-appstream-rpms 77 k
libXt x86_64 1.1.5-12.el8 rhel-8-for-x86_64-appstream-rpms 185 k
alsa-utils x86_64 1.1.9-1.el8 rhel-8-for-x86_64-appstream-rpms 1.1 M
...
podman-manpages noarch 1.4.2-5.module+el8.1.0+4240+893c1ab8 rhel-8-for-x86_64-appstream-rpms 180 k
python3-pip-wheel noarch 9.0.3-15.el8 rhel-8-for-x86_64-baseos-rpms 1.2 M
mozjs60 x86_64 60.9.0-3.el8 rhel-8-for-x86_64-baseos-rpms 6.7 M
libssh-config noarch 0.9.0-4.el8 rhel-8-for-x86_64-baseos-rpms 18 k
python3-setuptools-wheel noarch 39.2.0-5.el8 rhel-8-for-x86_64-baseos-rpms 289 k
Installing weak dependencies:
oddjob-mkhomedir x86_64 0.34.4-7.el8 rhel-8-for-x86_64-appstream-rpms 52 k
libvarlink x86_64 18-3.el8 rhel-8-for-x86_64-baseos-rpms 44 k
Transaction Summary
Install 17 Packages
Upgrade 646 Packages
Total download size: 1.2 G
Is this ok [y/N]:
Some 15min later I had my desktop in a much better shape:
And that’s it! I rebooted the server and my OS is RHEL 8.1 now:
greys@redhat:~ $ more /etc/redhat-release
Red Hat Enterprise Linux release 8.1 (Ootpa)
greys@redhat:~ $ uname -a
Linux redhat 4.18.0-147.0.3.el8_1.x86_64 #1 SMP Mon Nov 11 12:58:36 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Just as I published last Unix Tutorial Digest on November 5th, RHEL 8.1 release got shipped – think this is a great incremental release bringing a number of key improvements to the Red Hat Enterprise Linux 8.
RHEL 8 Release Cadence
Red Hat announced that going forward Red Hat Enterprise Linux OS will be receiving regular updates every 6 months. Since RHEL 8 release was in May 2019, this current RHEL 8.1 update is right on time, 6 months after.
RHEL 8.1 Improvements I Want To Try
There’s a number of great improvements in this release:
Live Kernel Patching with kpatch
SELinux profiles for containers and tbolt for Thunderbolt devices – will be cool to try on my RHEL 8 PC
Perhaps try RHEL 7.6 in-place upgrade to RHEL 8.1
Review rhel-system-roles and specifically the new storage role added in RHEL 8.1
I also want to try Red Hat Universal Base Image for RHEL 8 – it’s been around since initial release in May, I just never got the chance to have a look.
I’m hardly getting any chance to work on Sun/Oracle hardware and Solaris anymore, but still like tracking the releases. OpenIndiana is a free Solaris implementation based on the Illumos project, and OpenIndiana 2019.10 just got released.
Improvements in OpenIndiana 2019.10
Latest improvements from the Illumos project (namely illumos-gate)
Since reinstalling certain software packages on my Linux desktop, Linux laptop and Macbook a few times in the past months, I’m positively in love with the Homebrew project. Today I’ll share my understanding of its basic deployment modules: casks vs formulae.
What Homebrew does
Homebrew project is the magic behind brew command – it’s a software manager that assists with source-code and binary distributions of various software projects.
Specifically, brew is popular on macOS platform where most of software is traditionally installed using graphical user interface (GUI) or via AppleScript automation. Recent versions of macOS exposed a number of relevant interfaces via command line, but average user (and most of advanced users/developers) still had to resort to some enterprise level proprietary delivery and installation mechanism.
With the arrival of Homebrew, things got much easier. A typical software installation is now simpler and quite comparable to the number of steps required in other Unix and Unix-like operating systems:
This is mostly due to the fact that Homebrew supports both standard and third-party software using its own centralised approach to software packaging. Application owners define a formula for installing their software, get in touch with Homebrew team to add it to the project, and going forward things happen pretty much automatically.
In Linux world, many software packages are still distributed independently or have to make their way into a specific application/software store – so many small projects are hard to find.
brew formula
Each Open Source package integrated with Homebrew is configured using a brew formula. It’s a Ruby language based configuration file that explains how the software can be downloaded from GitHub or similar repository and then compiled.
class Htop < Formula
desc "Improved top (interactive process viewer)"
homepage "https://hisham.hm/htop/"
url "https://hisham.hm/htop/releases/2.2.0/htop-2.2.0.tar.gz"
sha256 "d9d6826f10ce3887950d709b53ee1d8c1849a70fa38e91d5896ad8cbc6ba3c57"
revision 1
bottle do
cellar :any
sha256 "c06ff60960f64f5c8395f53d7419cbcce2a22ee87f0cb0138352c8a88111d21c" => :catalina
sha256 "77aa302765353b4085dcad52356d3264183e06310dda8d5bac64642299ea2902" => :mojave
sha256 "0ebfb655b91566ba31f8effc94d642a43305ff95bdc9b30b46fadc132e2ced0c" => :high_sierra
sha256 "ed93b86f011de155c5d261b8c9cc9cb81fd0017667bf3ebe26ee090716bcd650" => :sierra
end
head do
url "https://github.com/hishamhm/htop.git"
depends_on "autoconf" => :build
depends_on "automake" => :build
depends_on "libtool" => :build
end
depends_on "pkg-config" => :build
depends_on "ncurses" # enables mouse scroll
def install
system "./autogen.sh" if build.head?
system "./configure", "--prefix=#{prefix}"
system "make", "install"
end
def caveats; <<~EOS
htop requires root privileges to correctly display all running processes, so you will need to run `sudo htop`.
You should be certain that you trust any software you grant root privileges.
EOS
end
test do
pipe_output("#{bin}/htop", "q", 0)
end
end
brew install
Installing software from brew formulae is easy:
$ brew install htop
brew cask
brew cask is an extension to standard brew based software management, it’s a type of formula that documents the process of installing a graphical application (and not entirely coincidentally closed-source software).
Similar to brew formula, cask defines where software can be downloaded and what dependenices it has, but specification is so flexible that you can even download binary packages from developer websites. If it’s a paid project, you’ll probably get a chance to download a trial copy (that you later can enable using a valid serial number for that software).
Here’s brew cask for my password manager of choice, 1Password:
I’ve used a number of screenshot applications on my computers in the last few years, and it’s a never ending search for the perfect balance of flexibility and performance. Today I’m testing a new approach using native macOS grab functionality together with Hazel app.
Hazel by Noodlesoft
In case you haven’t heard about it, Hazel is an unbelievably powerful and flexible file management and automation tool for macOS:
Hazel by Noodlesoft
You select incoming folders to process (in my screenshot: Downloads and Desktop) and then define rules for automatically processing files. Hazel is running in background, monitoring folders for matching rules you configured and applying them as it finds new files – within seconds of a new file matching a Hazel rule it gets dispatched.
Here’s just a few of the workflows I have:
Rename PDF files to a specific name based on some keywords found inside the PDF document itself (great for automatically renaming utility bills)
Move ISO file downloads into specific folder on my NAS server
Move large files from Downloads folder into special archive area on NAS (to save space on laptop)
Rename all sorts of files to include datestamp – great for making these files easily found from Bash scripts later
Common Issues with Screenshot Software
I’ve found that most screenshot making software (for macOS) is not flexible enough in one way or another:
many apps are using proprietary database for storing images instead of standard folder
there’s no easy way to add screenshots from other software or folders – so unless you used the app to make a screenshot (or retake a screenshot of an existing image file) – it won’t make it
lots of apps allow you to export and import images but metadata is lost (like the date/time when the screenshot was taken)
there’s the problem of bloating up apps too, so something that started as a perfect screenshot tool can become an unusable (for me) collection of all sorts of image and video capturing functinality that’s just too slow or complex to use any longer
The Problem with Cloud Sync
I would also like to have screenshots from different laptops and PCs to be synced if at all possible – and it’s quite hard to find a screenshot app capable of doing this intelligently enough.
There’s a few great solutions that are geared towards team work and collaboration, but the problem with them is I have to create separate account for each computer or that all the images end up in a cloud with potentially auto-generated links.
Approach I’m trying Today
I decided to try a much simpler approach:
use built-in screenshot tool in macOS
use Hazel app to auto-collect screenshots from Desktop and place them into Pictures/screenshots folder
use Hazel app to auto-rename screenshots for better file sorting
Use Finder for accessing the screenshots folder with previews
Configure folder processing rule in Hazel
Here’s how my rule looks:
Hazel processing for screenshots
macOS Finder settings for the screenshots folder
And these are the settings I’ve selected for the screenshots folders:
I think it’s working out nicely: all my screenshots are sorted by the date they’re taken, there’s image size indication and thumbnails large enough for quickly finding the screenshot I want:
screenshots folder in macOS Finder
Syncing screenshots folder
Documents folder is iCloud synced, so I’m hoping to configure this setup on both desktop and laptop, this way both of them will always have the same screenshot collection. Potentially, I can even use my Ubuntu 19.10 XPS laptop to capture screenshots into Dropbox folder, which can be processed by Hazel on macOS to import images.
That’s it for now! Let me know how you’re dealing with screenshots and what tools you use!
Pretty cool: I’ve just learned a very simple but rather useful trick that will certainly help with my basic home automation and shell scripting. mount command has an option to list filesystems by type.
List Mounted Filesystems by Type
Quite often your Linux/Unix system will have filesystems of different types: most likely it will be special types like proc or tmpfs along with a number of traditional (Linux) filesystem types like ext2/ext3/ext4 or xfs.
mount -t command helps list just the mounted filesystems of certain type.
For instance, here’s how I can see just the ext4 filesystems on one of my Linux servers:
greys@s2:~ $ mount -t ext4
/dev/md0 on / type ext4 (rw,relatime,stripe=256,data=ordered)
/dev/md1 on /var/log type ext4 (rw,relatime,stripe=256,data=ordered)
/dev/md2 on /storage type ext4 (rw,relatime,stripe=256,data=ordered)
/dev/md0 on /var/lib/docker/devicemapper type ext4 (rw,relatime,stripe=256,data=ordered)
And here’s how I can now easily confirm list of AFPFS network shares mounted from my NAS server on MacBook under macOS:
greys@MacBook-Pro:~ $ mount -t afpfs
//[email protected]/t3chstack on /Volumes/t3chstack (afpfs, nodev, nosuid, mounted by greys)
//[email protected]/Storage on /Volumes/Storage (afpfs, nodev, nosuid, mounted by greys)
//[email protected]/Stuff on /Volumes/Stuff (afpfs, nodev, nosuid, mounted by greys)
Unix Tutorial Digest: monthly digest of Unix/Linux topics
September and October 2019 have been so busy for me at work and at home that I posted less frequently than usual and also skipped the September Unix Tutorial Digest. All is good, lots of interesting developments at work and with my home office servers, so I’ve been reading a lot and preparing new material.
HTTP/3 is becoming a thing! Initial support for it is found in nginx, curl and major browsers now
PulseAudio 13.0 released – I still remember how tricky it was to get its early versions to work on my desktop 10 years ago. This package has made great progress since then! Modern codecs like Dolby TrueHD and DTS-HD Master Audio are supported in version 13.
VirtualBox 6.1 beta was released – will test VirtualBox on my Dell XPS laptop soon, 6.1 beta 2 is out now. Should be cool to export VMs right into (Oracle) cloud! On macOS I still prefer Parallels.
