Printing multiple PDF files from console with lp

Recently I wanted to print some PDF files containing sheet music. The tedious way to do that, would be to open them one by one in Evince and press the print button. Surely there must be a more efficient way to do that?

$ ls -l --human-readable *.pdf
-r--r--r-- 1 amedee amedee 217K apr 15  2020 'Arthur original.pdf'
-r--r--r-- 1 amedee amedee 197K apr 13  2020 'Canal en octobre.pdf'
-r--r--r-- 1 amedee amedee  14K apr 13  2020  DenAndro.pdf
-r--r--r-- 1 amedee amedee  42K apr 14  2020 'Doedel you do.pdf'
-r--r--r-- 1 amedee amedee  57K apr 13  2020  Flatworld.pdf
-r--r--r-- 1 amedee amedee  35K apr 16  2020 'Jump at the sun.pdf'
-r--r--r-- 1 amedee amedee 444K jun 19  2016 'Kadril Van Mechelen.pdf'
-r--r--r-- 1 amedee amedee  15K apr 13  2020  La-gavre.pdf
-r--r--r-- 1 amedee amedee  47K apr 13  2020 'Le petit déjeuner.pdf'
-r--r--r-- 1 amedee amedee 109K apr 13  2020  LesChaminoux__2016_04_24.cached.pdf
-r--r--r-- 1 amedee amedee 368K apr 13  2020 'Mazurka It.pdf'
-r--r--r-- 1 amedee amedee 591K apr 13  2020 'Narrendans uit Mater.pdf'
-r--r--r-- 1 amedee amedee 454K apr 13  2020 'Neverending jig.pdf'
-r--r--r-- 1 amedee amedee 1,1M apr 14  2020 'Red scissors.pdf'
-r--r--r-- 1 amedee amedee  35K apr 13  2020  Scottish-à-VirmouxSOL.pdf
-r--r--r-- 1 amedee amedee  76K apr 14  2020 'Tarantella Napolitana meest gespeelde versie.pdf'
-r--r--r-- 1 amedee amedee 198K apr 15  2020 'Zot kieken!.pdf'

There are 2 console commands for printing: lp and lpr. One comes from grandpa System V, the other from grandpa BSD, and both are included in CUPS. The nice thing about these commands is that they know how to interpret PostScript and PDF files. So this is going to be easy: just cd into the directory with the PDF files and print them all:

$ lp *.pdf
lp: Error - No default destination.

Oops. A quick Google search of this error message tells me that I don’t have a default printer.

Configuring a default printer

First I use lpstat to find all current printers:

$ lpstat -p -d
printer HP_OfficeJet_Pro_9010_NETWORK is idle.  enabled since za 12 mrt 2022 00:00:28
printer HP_OfficeJet_Pro_9010_USB is idle.  enabled since za 12 mrt 2022 00:00:17
no system default destination

I have a HP OfficeJet Pro 9012e printer, which Ubuntu recognizes as a 9010 series. Close enough. It’s connected over network and USB. I’m setting the network connection as default with lpoptions:

$ lpoptions -d $(lpstat -p -d | head --lines=1 | cut --delimiter=' ' --fields=2)
copies=1 device-uri=hp:/net/HP_OfficeJet_Pro_9010_series?ip=192.168.1.9 finishings=3 job-cancel-after=10800 job-hold-until=no-hold job-priority=50 job-sheets=none,none marker-change-time=0 media=iso_a4_210x297mm number-up=1 output-bin=face-down print-color-mode=color printer-commands=none printer-info printer-is-accepting-jobs=true printer-is-shared=true printer-is-temporary=false printer-location printer-make-and-model='HP Officejet Pro 9010 Series, hpcups 3.22.2' printer-state=3 printer-state-change-time=1649175159 printer-state-reasons=none printer-type=4124 printer-uri-supported=ipp://localhost/printers/HP_OfficeJet_Pro_9010_NETWORK sides=one-sided

I can then use lpq to verify that the default printer is ready:

$ lpq
HP_OfficeJet_Pro_9010_NETWORK is ready
no entries

Printing multiple files from console

I found that if I naively do lp *.pdf, then only the last file will be printed. That’s unexpected, and I can’t be bothered to find out why. So I just use ls and feed that to a while-loop. It’s quick and dirty, and using find+xargs would probably be better if there are “special” characters, but that’s not the case here.

There’s one caveat: when the PDF files are printed one by one, then the first page will be at the bottom of the paper stack, so I need to print them in reverse order.

$ ls --reverse *.pdf | while read f; do lp "$f"; done

With that command I got 17 print jobs in the printer queue, one for each file.

Now that I know how to print from console, I’ll probably do that more often. The man page of lp describes many useful printing options, like printing double sided:

$ lp -o media=a4 -o sides=two-sided-long-edge filename

The hunt for a kernel bug, part 4: git bisect

Now that I have a way to compile kernels from source, I want to find the exact commit where my input devices stop working. That means doing a git checkout of a certain commit, build the kernel, install it, reboot, select the new kernel in Grub, and see if my keyboard works. I am quite sure that I need to search between 5.13.0-22 and 5.13.0-23, but that’s still 634 commits!

$ git rev-list Ubuntu-5.13.0-22.22..Ubuntu-5.13.0-23.23 | wc --lines
634

This is where git bisect comes in. It’s sort of a wizard that guides you to find a bad commit. You tell it on which commit your software was known to work ok, and a commit where it doesn’t. It then picks a commit somewhere in the middle, you build your software and do your tests, and then tell git bisect if the result was good or bad. It will then give you a new commit to inspect, each time narrowing the search.

git-bisect-sumo-logic
git bisect

Let’s do this!

$ git bisect start
$ git bisect good Ubuntu-5.13.0-22.22
$ git bisect bad Ubuntu-5.13.0-23.23
Bisecting: 316 revisions left to test after this (roughly 8 steps)
[398351230dab42d654036847a49a5839705abdcb] powerpc/bpf ppc32: Fix BPF_SUB when imm == 0x80000000
$ git describe --long 
Ubuntu-5.13.0-22.22-317-g398351230dab

In this first step, I get the 317th commit after 5.13.0-22. Let’s compile that commit:

$ time make clean olddefconfig bindeb-pkg \
    --jobs=$(getconf _NPROCESSORS_ONLN) \
    LOCALVERSION=-$(git describe --long | tr '[:upper:]' '[:lower:]')

This creates 3 .deb packages in the directory above:

$ ls -1 ../*$(git describe --long | tr '[:upper:]' '[:lower:]')*.deb
../linux-headers-5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab_5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab-10_amd64.deb
../linux-image-5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab_5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab-10_amd64.deb
../linux-libc-dev_5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab-10_amd64.deb

I only need to install the headers and the image, libc-dev isn’t needed.

$ sudo dpkg --install ../linux-{headers,image}-*$(git describe --long | tr '[:upper:]' '[:lower:]')*.deb

Verify that the kernel files are in the /boot directory:

$ ls -1 /boot/*$(git describe --long | tr '[:upper:]' '[:lower:]')*
/boot/config-5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab
/boot/initrd.img-5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab
/boot/System.map-5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab
/boot/vmlinuz-5.13.19-ubuntu-5.13.0-22.22-317-g398351230dab

Now I can reboot, select the new kernel in Grub, and test the keyboard. With commit 317, the keyboard worked, so the first bad commit has to be somewhere between commit 317 and 634:

$ git bisect good ; git describe --long
Bisecting: 158 revisions left to test after this (roughly 7 steps)
[79b62d0bba892e8367cb46ca09b623c885852c29] drm/msm/a4xx: fix error handling in a4xx_gpu_init()
Ubuntu-5.13.0-22.22-475-g79b62d0bba89

Now it’s time again for make clean olddefconfig bindeb-pkg, dpkg --install and reboot. Turns out that commit 475 was a “bad” commit (one where the keyboard didn’t work):

$ git bisect bad ; git describe --long
Bisecting: 78 revisions left to test after this (roughly 6 steps)
[c3d35f3acc3a11b726959c7b2c25ab9e46310273] USB: serial: option: add Telit LE910Cx composition 0x1204
Ubuntu-5.13.0-22.22-396-gc3d35f3acc3a

I’m not going to describe all the steps in full detail, by now you should get the gist of it. This was the sequence of steps that git bisect gave me:

  • 317: good
  • 475: bad
  • 396: bad
  • 356: good
  • 376: good
  • 386: good
  • 391: bad
  • 388: bad
  • 387: bad

And then we finally get the first bad commit, the 387th commit after 5.13.0-22, Ubuntu-5.13.0-22.22-387-g0fc979747dec:

$ git bisect bad ; git describe --long
0fc979747dece96c189bc29ef604e61afbddfa2a is the first bad commit
commit 0fc979747dece96c189bc29ef604e61afbddfa2a
Author: Pavankumar Kondeti <pkondeti@codeaurora.org>
Date:   Fri Oct 8 12:25:46 2021 +0300

    xhci: Fix command ring pointer corruption while aborting a command
    
    BugLink: https://bugs.launchpad.net/bugs/1951880
    
    commit ff0e50d3564f33b7f4b35cadeabd951d66cfc570 upstream.
    
    The command ring pointer is located at [6:63] bits of the command
    ring control register (CRCR). All the control bits like command stop,
    abort are located at [0:3] bits. While aborting a command, we read the
    CRCR and set the abort bit and write to the CRCR. The read will always
    give command ring pointer as all zeros. So we essentially write only
    the control bits. Since we split the 64 bit write into two 32 bit writes,
    there is a possibility of xHC command ring stopped before the upper
    dword (all zeros) is written. If that happens, xHC updates the upper
    dword of its internal command ring pointer with all zeros. Next time,
    when the command ring is restarted, we see xHC memory access failures.
    Fix this issue by only writing to the lower dword of CRCR where all
    control bits are located.
    
    Cc: stable@vger.kernel.org
    Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
    Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
    Link: https://lore.kernel.org/r/20211008092547.3996295-5-mathias.nyman@linux.intel.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

 drivers/usb/host/xhci-ring.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)
Ubuntu-5.13.0-22.22-387-g0fc979747dec

At first sight the commit description is quite cryptic, and the actual code change doesn’t tell me a lot either. But it’s a change in drivers/usb/host/xhci-ring.c, and xhci stands for eXtensible Host Controller Interface, and interface specification for USB host controllers. If it’s an issue with the USB host controller, then it makes sense that if I use 2 keyboards from different brands, neither of them would work. It also suggests that other USB devices, like external hard drives, wouldn’t work either, but that’s a bit harder to test. A keyboard is easy. Just look at NumLock LED, if it doesn’t go on then there’s an issue.

The first link in the commit description is just a long list of patches that were taken from upstream and integrated in the Ubuntu kernel, so that doesn’t help me. The second link is a thread on the kernel.org mailing list, and there it gets interesting.

kernel.org mailing list thread

Some excerpts from the thread:

This patch cause suspend to disk resume usb not work, xhci_hcd 0000:00:14.0: Abort failed to stop command ring: -110.

youling257

Thanks for the report, this is odd.
Could you double check that by reverting this patch resume start working again.
If this is the case maybe we need to write all 64bits before this xHC hardware reacts to CRCR register changes.
Maybe following changes on top of current patch could help:

Mathias Nyman

Every time a developer says “this is odd”, my alarm bells go off. 😀

Further down in the thread there is a proposed update to the change. I’m going to try that patch, but that’s for another blog post.

The hunt for a kernel bug, part 3: compiling a kernel

Compiling a Linux kernel sounds scary and complicated, but I found out it actually isn’t.

The first thing to do, is to install some prerequisites:

$ sudo apt install --yes asciidoc binutils-dev bison build-essential ccache \
    crash dwarves fakeroot flex git git-core git-doc git-email kernel-package \
    kernel-wedge kexec-tools libelf-dev libncurses5 libncurses5-dev libssl-dev \
    makedumpfile zstd
$ sudo apt-get --yes build-dep linux

Next I cloned the Ubuntu Impish repository. This takes a while…

$ git clone git://kernel.ubuntu.com/ubuntu/ubuntu-impish.git
$ cd ubuntu-impish

Now let’s see which versions are in the repository:

$ git tag --list
Ubuntu-5.11.0-16.17
Ubuntu-5.11.0-18.19+21.10.1
Ubuntu-5.11.0-20.21+21.10.1
Ubuntu-5.13.0-11.11
Ubuntu-5.13.0-12.12
Ubuntu-5.13.0-13.13
Ubuntu-5.13.0-14.14
Ubuntu-5.13.0-15.15
Ubuntu-5.13.0-16.16
Ubuntu-5.13.0-17.17
Ubuntu-5.13.0-18.18
Ubuntu-5.13.0-19.19
Ubuntu-5.13.0-20.20
Ubuntu-5.13.0-21.21
Ubuntu-5.13.0-22.22
Ubuntu-5.13.0-23.23
Ubuntu-5.13.0-24.24
Ubuntu-5.13.0-25.26
Ubuntu-5.13.0-26.27
Ubuntu-5.13.0-27.29
Ubuntu-5.13.0-28.31
Ubuntu-5.13.0-29.32
Ubuntu-5.13.0-30.33
Ubuntu-5.13.0-31.34
Ubuntu-5.13.0-32.35
freeze-20211018
freeze-20211108
freeze-20220131
freeze-20220221
v5.11
v5.13

The two tags that interest me, are Ubuntu-5.13.0-22.22 and Ubuntu-5.13.0-23.23. I’m starting with the former.

git checkout Ubuntu-5.13.0-22.22

First I copy the configuration of the current running kernel to the working directory:

$ cp /boot/config-$(uname --kernel-release) .config

I don’t want or need full debugging. That makes an enormous kernel and it takes twice as long to compile, so I turn debugging off:

$ scripts/config --disable DEBUG_INFO

I need to disable certificate stuff:

$ scripts/config --disable SYSTEM_TRUSTED_KEYS
$ scripts/config --disable SYSTEM_REVOCATION_KEYS

Next: update the kernel config and set all new symbols to their default value.

$ make olddefconfig

Then the most exciting thing can start: actually compiling the kernel!

$ make clean
$ time make --jobs=$(getconf _NPROCESSORS_ONLN) bindeb-pkg \
    LOCALVERSION=-$(git describe --long | tr '[:upper:]' '[:lower:]')
  • time is to see how long the compilation took.
  • getconf _NPROCESSORS_ONLN queries the number of processors on the computer. make will then try to run that many jobs in parallel.
  • bindeb-pkg will create .deb packages in the directory above.
  • LOCALVERSION appends a string to the kernel name.
  • git describe --long shows how far after a tag a certain commit is. In this case: Ubuntu-5.13.0-22.22-0-g3ab15e228151
    • Ubuntu-5.13.0-22.22 is the tag.
    • 0 is how many commits after the tag. In this case it’s the tag itself.
    • 3ab15e228151 is the abbreviated hash of the current commit.
  • tr '[:upper:]' '[:lower:]' is needed because .deb packages can’t contain upper case letters (I found out the hard way).

Now go grab a coffee, tea or chai latte. Compilation took 22 minutes on my computer.

Chai latte

When the compilation is done, there are 3 .deb packages in the directory above:

$ ls -1 ../*.deb
../linux-headers-5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151_5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151-21_amd64.deb
../linux-image-5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151_5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151-21_amd64.deb
../linux-libc-dev_5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151-21_amd64.deb

Install the linux-headers and the linux-image packages, you don’t need the libc-dev package.

$ sudo dpkg --install \
    ../linux-{headers,image}-*$(git describe --long | tr '[:upper:]' '[:lower:]')*.deb

The kernel is now installed in the /boot directory, and it’s available in the Grub menu after reboot.

$ ls -1 /boot/*$(git describe --long | tr '[:upper:]' '[:lower:]')*
/boot/config-5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151
/boot/initrd.img-5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151
/boot/System.map-5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151
/boot/vmlinuz-5.13.19-ubuntu-5.13.0-22.22-0-g3ab15e228151

Kernel ubuntu-5.13.0-22.22-0-g3ab15e228151 is, for all intents and purposes, the same as kernel 5.13.0-22-generic, so I expected it to be a “good” kernel, and it was.

For kernel Ubuntu-5.13.0-23.23 I did the same thing: starting from the git checkout. I skipped copying and editing the config file, because between minor releases I don’t expect there to be much change. I did run make olddefconfig for good measure, though. As expected, the keyboard and mouse didn’t work with the compiled ...-23 kernel.

Next up: using git bisect to find the exact commit where it went wrong. It’s got to be somewhere between ...-22 and ...-23!

The hunt for a kernel bug, part 2: an easy way to install mainline kernels

As I wrote previously, I’m suspecting a Linux kernel bug somewhere between versions 5.13.0-22 and 5.13.0-23, in the Ubuntu kernels. I wanted to know if the issue only surfaced in Ubuntu-flavored kernels, or also in the upstream (mainline) kernels from kernel.org.

There is an Ubuntu Mainline PPA with all the upstream kernels, but I found it a bit too opaque to use. Fortunately I found the Ubuntu Mainline Kernel Installer (UMKI), a tool for installing the latest Linux kernels on Ubuntu-based distributions.

Ubuntu Mainline Kernel Installer (UMKI)

The UMKI is pretty straightforward. It fetches a list of kernels from the Ubuntu Mainline PPA and a GUI displays available and installed kernels, regardless of how they were installed. It installs the kernel, headers and modules. There is also a CLI client.

To install the UMKI:

sudo add-apt-repository ppa:cappelikan/ppa
sudo apt update
sudo apt install mainline

With that out of the way, there’s the matter of deciding which kernels to try. The “interesting” Ubuntu kernels are 5.13.0-22 and 5.13.0-23, so the mainline kernels I definitely want to test, are around those versions. That means 5.13.0 and 5.13.1. I also want to try the latest 5.13.x kernel, so that’s 5.13.19, and the most recent stable kernel, 5.16.11 (as of 2022-03-01).

To summarize, I have tested these mainline kernels:

  • 5.13.0
  • 5.13.1
  • 5.13.19
  • 5.16.11

The result (after several reboots)? With all of them, my keyboard and mouse worked without a hitch. That means the issue most likely doesn’t occur in (stable) mainline kernels, only in kernels with additional patches from Ubuntu.

Up next: compiling kernels from source.

Lasciate ogne speranza, voi ch’intrate.

Dante Alighieri

The hunt for a kernel bug, part 1

The operating system on my computer is Ubuntu Linux, version 21.10 (Impish Indri). Recently I had an issue that, after a kernel update (and reboot), my USB keyboard and mouse didn’t work any more in the login screen. Huh, that’s unexpected.
The issue was:

  • At the Grub boot menu, the keyboard works: I can use the keys, the numlock led lights up, the LCD of the Logitech G19 displays a logo.
  • At the Ubuntu login screen, the keyboard (and the mouse) went dark: no backlight of the keys, no numlock led, no logo on the display. And the mouse cursor didn’t move on screen.

Must be a problem at my end, I initially thought, because surely, something so essential as input devices wouldn’t break by a simple kernel update? So I did some basic troubleshooting:

  • Have you tried to turn it off and on again?
Have you tried to turn it off and on again?
Have you tried to turn it off and on again?
  • Plug the keyboard in another USB port.
  • Try a different keyboard.
  • Start with the older kernel, which was still in the Grub menu. And indeed, this gave me back control over my input devices!

So if the only thing I changed was the kernel, then maybe it’s a kernel bug after all?

I know that Ubuntu 21.10 uses kernel 5.something, and I know that I use the generic kernels. So which kernels are we talking about, actually?

$ apt-cache show linux-image-5*-generic | grep Package: | sed 's/Package: //g'
linux-image-5.13.0-19-generic
linux-image-5.13.0-20-generic
linux-image-5.13.0-21-generic
linux-image-5.13.0-22-generic
linux-image-5.13.0-23-generic
linux-image-5.13.0-25-generic
linux-image-5.13.0-27-generic
linux-image-5.13.0-28-generic
linux-image-5.13.0-30-generic

9 kernels, that’s not too bad. All of them 5.13.0-XX-generic. So I just installed all the kernels:

$ sudo apt install --yes \
    linux-{image,headers,modules,modules-extra,tools}-5.13.0-*-generic
One Eternity Later

My /boot directory is quite busy now:

$  ls -hl /boot
total 1,2G
drwxr-xr-x  4 root root  12K mrt  1 18:11 .
drwxr-xr-x 20 root root 4,0K mrt  1 18:11 ..
-rw-r--r--  1 root root 252K okt  7 11:09 config-5.13.0-19-generic
-rw-r--r--  1 root root 252K okt 15 15:53 config-5.13.0-20-generic
-rw-r--r--  1 root root 252K okt 19 10:41 config-5.13.0-21-generic
-rw-r--r--  1 root root 252K nov  5 10:21 config-5.13.0-22-generic
-rw-r--r--  1 root root 252K nov 26 12:14 config-5.13.0-23-generic
-rw-r--r--  1 root root 252K jan  7 16:16 config-5.13.0-25-generic
-rw-r--r--  1 root root 252K jan 12 15:43 config-5.13.0-27-generic
-rw-r--r--  1 root root 252K jan 13 18:13 config-5.13.0-28-generic
-rw-r--r--  1 root root 252K feb  4 17:40 config-5.13.0-30-generic
drwx------  4 root root 4,0K jan  1  1970 efi
drwxr-xr-x  5 root root 4,0K mrt  1 18:11 grub
lrwxrwxrwx  1 root root   28 feb 28 04:26 initrd.img -> initrd.img-5.13.0-22-generic
-rw-r--r--  1 root root  40M mrt  1 16:02 initrd.img-5.13.0-19-generic
-rw-r--r--  1 root root  40M mrt  1 17:39 initrd.img-5.13.0-20-generic
-rw-r--r--  1 root root  40M mrt  1 17:38 initrd.img-5.13.0-21-generic
-rw-r--r--  1 root root  40M feb 26 13:55 initrd.img-5.13.0-22-generic
-rw-r--r--  1 root root  40M mrt  1 17:40 initrd.img-5.13.0-23-generic
-rw-r--r--  1 root root  40M mrt  1 17:40 initrd.img-5.13.0-25-generic
-rw-r--r--  1 root root  40M mrt  1 17:41 initrd.img-5.13.0-27-generic
-rw-r--r--  1 root root  40M mrt  1 17:41 initrd.img-5.13.0-28-generic
-rw-r--r--  1 root root  40M mrt  1 17:38 initrd.img-5.13.0-30-generic
-rw-------  1 root root 5,7M okt  7 11:09 System.map-5.13.0-19-generic
-rw-------  1 root root 5,7M okt 15 15:53 System.map-5.13.0-20-generic
-rw-------  1 root root 5,7M okt 19 10:41 System.map-5.13.0-21-generic
-rw-------  1 root root 5,7M nov  5 10:21 System.map-5.13.0-22-generic
-rw-------  1 root root 5,7M nov 26 12:14 System.map-5.13.0-23-generic
-rw-------  1 root root 5,7M jan  7 16:16 System.map-5.13.0-25-generic
-rw-------  1 root root 5,7M jan 12 15:43 System.map-5.13.0-27-generic
-rw-------  1 root root 5,7M jan 13 18:13 System.map-5.13.0-28-generic
-rw-------  1 root root 5,7M feb  4 17:40 System.map-5.13.0-30-generic
lrwxrwxrwx  1 root root   25 feb 28 04:27 vmlinuz -> vmlinuz-5.13.0-22-generic
-rw-------  1 root root 9,8M okt  7 19:37 vmlinuz-5.13.0-19-generic
-rw-------  1 root root 9,8M okt 15 15:56 vmlinuz-5.13.0-20-generic
-rw-------  1 root root 9,8M okt 19 10:43 vmlinuz-5.13.0-21-generic
-rw-------  1 root root 9,8M nov  5 13:51 vmlinuz-5.13.0-22-generic
-rw-------  1 root root 9,8M nov 26 11:52 vmlinuz-5.13.0-23-generic
-rw-------  1 root root 9,8M jan  7 16:19 vmlinuz-5.13.0-25-generic
-rw-------  1 root root 9,8M jan 12 16:19 vmlinuz-5.13.0-27-generic
-rw-------  1 root root 9,8M jan 13 18:10 vmlinuz-5.13.0-28-generic
-rw-------  1 root root 9,8M feb  4 17:46 vmlinuz-5.13.0-30-generic

I tried all these kernels. The last kernel where my input devices still worked, was 5.13.0-22-generic, and the first where they stopped working, was 5.13.0-23-generic. Which leads me to assume that some unintended change was introduced between those two versions, and it hasn’t been fixed since.

For now, I’m telling Ubuntu to keep kernel 5.13.0-22-generic and not upgrade to a more recent version.

$ sudo apt-mark hold linux-image-5.13.0-22-generic
linux-image-5.13.0-22-generic set on hold.

I also want Grub to show me the known working kernel as the default change. To do that, I’ve put this in /etc/default/grub:

GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux 5.13.0-22-generic"

followed by sudo update-grub.

I’ll do the following things next, to get to the bottom of this:

How I organize my message flow

Email

I use 2 email clients at the same time: Thunderbird and Gmail.

  • Thunderbird: runs on my local system, it’s very fast, it shows me all the metadata of an email in the way I want, the email list is not paged, I can use it for high volume actions on email. These happen on my local system, and then the IMAP protocol gradually syncs it to Gmail. I also find that Thunderbird’s email notifications integrate nicer in Ubuntu.
  • Gmail: can’t be beaten for search. It also groups mail conversations. And then there are labels!
How to turn on Conversation View in Gmail

Gmail has several tabs: Primary, Social, Promotions, Updates and Forums. Gmail is usually smart enough that it can classify most emails in the correct tab. If it doesn’t: drag the email to the correct tab, and Gmail will ask you if all future emails of that sender should go to the same tab. This system works well enough for me. My email routine is to first check the tabs Social, Promotions and Forums, and delete or unsubscribe from most emails that end up there. All emails about the #jobhunt go to Updates. I clean up the other emails in that tab (delete, unsubscribe, filter, archive) so that only the #jobhunt emails remain. Those I give a label – more about that later. Then I go to the Inbox. Any emails there (shouldn’t be many) are also taken care of: delete, unsubscribe, filter, archive or reply.

Enable Gmail tabs
Gmail tabs

Google has 3 Send options: regular Send, Schedule send (which I don’t use) and Send + Archive. The last one is probably my favorite button. When I reply to an email, it is in most cases a final action on that item, so after the email is sent, it’s dealt with, and I don’t need to see it in my Inbox any more. And if there is a reply on the email, then the entire conversation will just go to the Inbox again (unarchived).

Send + Archive

I love labels! At the level of an individual email, you can add several labels. The tabs are also labels, so if you add the label Inbox to an archived email, then it will be shown in the Inbox again. At the level of the entire mailbox, labels behave a bit like mail folders. You can even have labels within labels, in a directory structure. Contrary to traditional mail clients, where an email could only be in one mail folder, you can add as many labels as you want.
The labels are also shown as folders in an IMAP mail client like Thunderbird. If you move an email from one folder to another, then the corresponding label gets updated in Gmail.
The filters that I use in my #jobhunt are work/jobhunt, work/jobhunt/call_back, work/jobhunt/not_interesting, work/jobhunt/not_interesting/freelance, work/jobhunt/not_interesting/abroad, work/jobsites and work/coaching. The emails that end up with the abroad label, are source material for my blog post Working Abroad?

The label list on the left looks like a directory structure. It’s actually a mix of labels and traditional folders like Sent, Drafts, Spam, Trash,… Those are always visible at the top. Then there is a neat little trick for labels. If you have a lot of labels, like me, then Gmail will hide some of them behind a “More” button. You can influence which labels are always visible by selecting Show if unread on that label. This only applies to top-level labels. When there are no unread emails with that label or any of it’s sublabels, then the label will be hidden below the More button. As soon as there are unread mails with that label or any of it’s sublabels, then the label will be visible. Mark all mails as read, and the label is out of view. Again, less clutter, you only see it when you need it.

Show if unread

Filters, filters, filters. I think I have a gazillion filters. (208, actually – I exported them to XML so I could count them) Each time I have more than two emails that have something meaningful in common, I make a filter. Most of my filters have the setting ‘Skip Inbox’. They will remain unread in the label where I put them, and I’ll read them when it’s convenient for me. For example, emails that are automatically labelled takeaway aren’t important and don’t need to be in the Inbox, but when I want to order takeaway, I take a look in that folder to see if there are any promo codes.

Email templates. Write a draft email, click on the 3 dots bottom right, save draft as template. Now I can reuse the same text so that I don’t have to write for the umpteenth time that I don’t do freelance. I could send an autoreply with templates, but for now I’ll still do it manually.

LinkedIn

I can be short about that: it’s a mess. You can only access LinkedIn messages from the website, and if you have a lot of messages, then it behaves like a garbage pile. Some people also have an expectation that it’s some sort of instant messaging. For me it definitely isn’t. And just like with email: I archive LinkedIn chats as soon as I have replied.

I used to have an autoreply that told people to email me, and gave a link to my CV and my blog. What do you think, should I enable that again?

A small rant about dependencies (and a promise)

Every now and then I run into some awesome open source project on GitHub, that is written in some cool programming language, and it assumes that the development tools for that language are already installed. My assumption is that they have a specific target audience in mind: an already existing developer community around that specific language. People who already have those tools installed.

The annoying thing is when someone like me, who doesn’t really need to know if a thing is written in Python or Ruby or JavaScript or whatever, tries to follow instructions like these:

$ pip install foo
Command 'pip' not found
$ gem install bar
Command 'gem' not found
$ yarn install baz
Command 'yarn' not found
$ ./configure && make && sudo make install
Command 'make' not found

By now, I already know that I first need to do sudo apt install python3-pip (or the equivalent installation commands for RubyGems, Yarn, build-essential,…). I also understand that, within the context of a specific developer community, this is so obvious that it is often assumed. That being said, I am making a promise:

For every open source project that I will henceforth publish online (on Github or any other code sharing platforms), I promise to do the following things:
(1) Test the installation on at least one clean installed operating system – which will be documented.
(2) Include full installation steps in the documentation, including all frameworks, development tools, etc. that would otherwise be assumed.
(3) Where possible and useful, provide an installation script.

The operating system I’m currently targeting, is Ubuntu, which means I’ll include apt commands. I’m counting on Continuous Integration to help me test on other operating systems that I don’t personally use.

What are my preferred roles?

Definitely a halfling barbarian. Alignment: chaotic neutral.

Oh, you didn’t mean tabletop role playing but job roles? Riiiight…

I don’t think that this blog post will ever be complete, and it will always be evolving. But at this point, some of the things that I see myself doing:


Anything related to Continuous Delivery in software. From my perspective, that may include:

  • Test Automation – I’ve done this a lot, I liked it and wouldn’t mind doing more of it.
  • DevOps – I’m still not sure if DevOps must be a separate role, or if other roles can work better if they apply DevOps principles. That being said, I have done some devops-ish things, I liked it, and I would sure like to do more of it.
  • Software Development – There, I’ve put it in writing. I haven’t done this yet in a work context, but I like doing it and learning about it. And really – isn’t test automation also writing software?

Maybe you noticed that in none of these things I mention a specific technology. There may be tech&tools that I already have experience with, and you can read about that in my CV or on LinkedIn, but that is not what this blog post is about. I believe that technologies can (and should) always be learned, and it’s more of an attitude to work quality-driven.


Technical Storytelling or Technical Community Management
Storytelling can help simplify the complexities of new technologies. It’s a combination of technical skills, communication skills and empathy. It’s about supporting a community by creating helpful content, from sample code to tutorials, blog posts(*) and videos; speaking at conferences; and helping improve a product or technology by collecting feedback from the community. I recently read a blog post on this, and I can totally recognize myself there.

(*) Yes, the blog posts that I’m writing now, are also written with that kind of role in mind.


Also have a look at the roles that I am not interested in (but do get a lot of emails about).

What is my preferred region?

When recruiters contact me, I invariably get asked in what region I am willing to work. Well. It depends.
(scroll down for a map if you don’t want to read).

The thing is, I actually enjoy going from point A to point B. At the same time, if it is in much less than ideal situations (lots of traffic, or crowded public transportation), then I may get overstimulated, which leads to fatigue and lack of concentration. The least enjoyable commute was only 20km, by car, but it typically took me more than one hour. This was when a new bridge was constructed over the Scheldt in Temse.

The most pleasant work experiences I had, involved these commute patterns:

  • A 3km bicycle ride (about 10 minutes).
  • 30 km by car, with the first 15 minutes on almost empty rural roads, and then 25 minutes on a highway in the direction that had the least amount of traffic.
  • 5km, which I did on foot in 50 minutes (I was training for the Dodentocht at the time).
  • 40km, which I did with 5 minutes bicycle, 35 minutes train, 5 minutes walking. Ideal for listening to one or two episodes of a podcast. Doing the same distance by car would taken me about the same amount of time, in ideal conditions. And I can’t focus on traffic and listen to a podcast at the same time.
  • 6km, which was 20 minutes on a bicycle or 12 minutes by car. I preferred cycling, because I had separate bike lanes for about 80% of the way. 20 minutes was also an ideal amount of time to listen to one epidode of a podcast.

That looks like a lot of cycling, even though I don’t really consider myself to be an athletic type. It’s also eco-friendly, even though I don’t really consider myself to be an eco-warrior.

I’m not a petrol head, I don’t know anything about cars. 4 wheels and steering wheel, that’s about the limit of my knowledge. Currently I don’t even have a car, I make use of car sharing services like Cambio on the rare occasions that I actually need a car. At the same time, I do enjoy the experience of driving, especially long, smooth stretches. For example each year I go to a music course somewhere in the middle of Germany. That’s a 5 hour drive, not including stops. I absolutely love the change of scenery along the way. But but me in city traffic for an hour and I get too much input.

I have found a website where you can draw a map of the places you can reach within a certain time: TravelTime (the also have an API! ❤️).

This is a map I made with the following data:

  • Yellow: reachable by cycling in 30 minutes or less. That’s about all of the city center of Ghent.
  • Red: reachable by public transport in 1 hour or less. That doesn’t get me to Antwerp, Mechelen or Kortrijk, but Brussels and Bruges are just about reachable.
  • Blue: reachable by car in 45 minutes or less. That barely touches Antwerp. Brussels: the north, west and south edges. Kortrijk and Bruges are also within reach. Why the cutoff at 45 minutes? Well, I would need really, really good other motivations to consider Brussels. Some time ago I thought that 30 minutes would be my maximum, but it isn’t. I’d rather call it an optimum than a maximum.
TravelTime

Even with this map, I still have a personal bias. Most of my social life occurs somewhere in the triangle Ghent-Antwerp-Brussels. It becomes harder to do something after work when working in West-Flanders. It’s not a hard pass, just a preference.

I have more to tell on this topic, so I might update this blog post later.

Installing Ubuntu 20.04 LTS on 2011 MacBook Air

My laptop is a 2011 MacBook Air. I’m not a huge Apple fan, it’s just that at the time it had the most interesting hardware features compared to similar laptops. And it’s quite sturdy, so that’s nice.

Over the years I have experimented with installing Linux in parallel to the OS X operating system, but in the end I settled on installing my favorite Linux tools inside OS X using Homebrew, because having two different operating systems on one laptop was Too Much Effort. In recent times Apple has decided, in it’s infinite wisdom (no sarcasm at all *cough*), that it will no longer provide operating system upgrades for older hardware. Okay, then. Lately the laptop had become slow as molasses anyway, so I decided to replace OS X entirely with Ubuntu. No more half measures! I chose 20.04 LTS for the laptop because reasons. 🙂

The laptop was really slow…

According to the Ubuntu Community Help Wiki, all hardware should be supported, except Thunderbolt. I don’t use anything Thunderbolt, so that’s OK for me. The installation was pretty straightforward: I just created a bootable USB stick and powered on the Mac with the Option/Alt (⌥) key pressed. Choose EFI Boot in the Startup Manager, and from there on it’s all a typical Ubuntu installation.

screenshot
Startup Manager

I did not bother with any of the customizations described on the Ubuntu Wiki, because everything worked straight out of the box, and besides, the wiki is terribly outdated anyway.

The end result? I now have a laptop that feels snappy again, and that still gets updates for the operating system and the installed applications. And it’s my familiar Linux. What’s next? I’m thinking about using Ansible to configure the laptop.

To finish, I want to show you my sticker collection on the laptop. There’s still room for a lot more!

sticker collection on my laptop. Photo copyright: me.