Going to the first matching tag in vim with Control-]
can be rather
annoying. The exuberant-ctags
secondary sort key is the filename, not
the tag kind. If you have a struct type that’s also a common member
name, you’re forced into using :tselect
to find the struct instead of
all the members. Most of the time, the struct definition is what you
want.
To avoid this issue, I sort the tags file such that any kind == "s"
entries come first for that tag. It’s a little annoying due to the
format of the file, but it does work:
#!/bin/bash
# ctags, but sub-sorted such that "struct request" comes first, rather than
# members with the same name.
# we can't use "-f -", as that elides the TAG_FILE_SORTED preamble
ctags -R -f tags.$$
awk '
BEGIN {
FS="\t"
entry=""
struct=""
buf=""
}
$1 != entry {
if (entry != "") {
printf("%s%s", struct, buf);
}
entry=$1;
struct="";
buf="";
}
/^.*"\ts/ {
struct=struct $0 "\n"
next
}
$1 == entry {
buf=buf $0 "\n"
}
END {
printf("%s%s", struct, buf);
}' <tags.$$ >tags
rm tags.$$
With all this free time I finally got around to installing a doorbell at
home. I had no interest in Ring or the like: what I really wanted was a
simple push doorbell that fit the (Victorian) house but would also
somehow notify me if I was downstairs…
There are several documented projects on splicing in a Raspberry Pi into
existing powered doorbell systems, but that wasn’t what I wanted either.
Instead, the doorbell is a simple contact switch feeding into the Pi’s
GPIO pins. It’s effectively extremely simple but I didn’t find a step by
step, so this is what I could have done with reading.
I bought the Pi, a case, a power supply, an SD card, and a USB speaker:

And the doorbell itself plus wiring:

I bought a pre-installed Raspbian SD card as I don’t have an SD card
caddy. After some basic configuration (which required HDMI over to a
monitor) I started playing with how to set up the Pi.
Of course the PI is absurdly over-powered for this purpose, but I wanted
something simple to play with. And anyway, it’s running Pihole too.
The wiring itself is simple: bell wire over through a hole in the door
frame to the back of the doorbell (which is a simple contact push). The
other end of the wires are connected to the PI’s GPIO pin 18, and
ground.
The pin is pulled up and we trigger the event when we see a falling
edge.
Actually connecting the wires was a bit fiddly: the bell wire is too
thin for the 0.1" connector, and lacking a proper crimping tool I had to
bodge it with needle-nose pliers. But once in the pins the housing
connection is solid enough.
At first I tried to connect it to Alexa but soon gave up on that idea.
There’s no way to “announce” via any API, and it kept disconnecting when
used as a Bluetooth speaker. And Alexa has that infuriating “Now playing
from…” thing you can’t turn off as well.
During fiddling with this I removed PulseAudio from the Pi as a dead
loss.
Nor could I use an Anker Soundcore as a Bluetooth speaker: the stupid
thing has some sleep mode that means it misses off the first 3 seconds
or so of whatever’s playing.
Instead I have the USB speaker above. It’s not great but is enough to be
heard from outside and inside.
Aside from playing whatever through the speaker, the bell notifies my
desktop as well as sending an email. Here’s the somewhat crappy script
it’s running:
#!/usr/bin/python3 -u
#
# Not going to win any awards this one, is it?
#
# The Pi is wired up such that pin 18 goes through the switch to ground.
# The on-pin pull-up resistor is enabled (so .input() is normally True).
# When the circuit completes, it goes to ground and hence we get a
# falling edge and .input() becomes False.
#
# I get the occasional phantom still so we wait for settle_time before
# thinking it's real.
#
from email.mime.text import MIMEText
from subprocess import Popen, PIPE
from datetime import datetime
import RPi.GPIO as GPIO
import subprocess
import alsaaudio
import threading
import signal
import wave
import time
import sys
import os
samplefile = sys.argv[1]
device='plughw:1,0'
# in seconds
settle_time = 0.1
bounce_time = 1
active = False
def notify():
subprocess.run(['/home/pi/notify-sent'])
msg = MIMEText('At %s' % datetime.now().strftime('%Y-%m-%d %H:%M:%S'))
msg['From'] = 'doorbell <[email protected]>'
msg['To'] = 'John Levon <[email protected]>'
msg['Subject'] = 'Someone is ringing the doorbell'
p = Popen(['/usr/sbin/sendmail', '-f', '[email protected]', '-t', '-oi'], stdin=PIPE)
p.stdin.write(msg.as_string().encode())
p.stdin.close()
def play():
global samplefile
global active
active = True
count = 0
with wave.open(samplefile) as f:
format = None
# 8bit is unsigned in wav files
if f.getsampwidth() == 1:
format = alsaaudio.PCM_FORMAT_U8
# Otherwise we assume signed data, little endian
elif f.getsampwidth() == 2:
format = alsaaudio.PCM_FORMAT_S16_LE
elif f.getsampwidth() == 3:
format = alsaaudio.PCM_FORMAT_S24_3LE
elif f.getsampwidth() == 4:
format = alsaaudio.PCM_FORMAT_S32_LE
else:
raise ValueError('Unsupported format')
rate = f.getframerate()
periodsize = rate // 8
out = alsaaudio.PCM(alsaaudio.PCM_PLAYBACK, device=device)
out.setchannels(f.getnchannels())
out.setrate(rate)
out.setformat(format)
out.setperiodsize(periodsize)
# We always play at least one time round...
while active or count < 1:
data = f.readframes(periodsize)
if data:
out.write(data)
else:
print('looping after %d plays, active %s' % (count, active))
count += 1
f.rewind()
print('pausing audio')
out.pause()
print('stopped after %d plays' % count)
def wait():
global active
while True:
input_state = GPIO.input(18)
if input_state:
print('got input_state %s, active -> False' % input_state)
active = False
break
time.sleep(0.2)
def trigger():
print('triggering at %s' % time.time())
tn = threading.Thread(target=notify)
tn.start()
tp = threading.Thread(target=play)
tp.start()
tw = threading.Thread(target=wait)
tw.start()
tw.join()
tp.join()
tn.join()
def settle():
global settle_time
time.sleep(settle_time)
input_state = GPIO.input(18)
print('input state now %s' % input_state)
return not input_state
def falling_edge(channel):
input_state = GPIO.input(18)
print('got falling edge, input_state %s' % input_state)
if settle():
trigger()
with wave.open(samplefile) as f:
# things go horrible if the rate isn't 48000 for some reason
if f.getframerate() != 48000:
raise ValueError('file must be 48000 rate')
if f.getsampwidth() not in [ 1, 2, 3, 4]:
raise ValueError('Unsupported format')
GPIO.setmode(GPIO.BCM)
GPIO.setup(18, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.add_event_detect(18, GPIO.FALLING, callback=falling_edge, bouncetime=(bounce_time * 1000))
print('started')
signal.pause()
For some time now, gnome-terminal
amongst others has had a heuristic
that guesses at URLs, and allows you to control-click to directly open
it. However, this was easily foxed by applications doing line-wrapping
instead of letting the terminal do so.
A few years ago, gnome-terminal
gained ANSI escape sequences for URL
highlighting.
It requires applications to output the necessary escape codes, but works
far more reliably.
Annoyingly, you still need to control-click, but that is easily
fixed.
I rebuilt Ubuntu’s build with this change like so:
sudo apt build-dep gnome-terminal
apt source gnome-terminal
cd gnome-terminal-3.28.2
dpkg-buildpackage --no-sign -b
sudo dpkg -i ../gnome-terminal_3.28.2-1ubuntu1~18.04.1_amd64.deb
This would be most useful if mutt
supported the sequences, but
unfortunately its built-in pager is stuck behind libncurses
and can’t
easily get out from under it. Using an external pager with mutt
is not
great either, as you lose all the integration.
There’s also no support in
w3m
. Even though it
thankfully avoids libncurses
, it’s a bit of a pain to implement, as
instead of just needing to track individual bits for bold on/off or
whatever, there’s a whole URL target that needs mapping onto the
(re)drawn screen lines.
So instead there’s the somewhat ersatz:
$ grep email-html ~/.muttrc
macro pager,index,attach k "<pipe-message>email-html<Enter>"
where
$ cat email-html
#!/bin/bash
dir=$(mktemp -d -p /tmp)
ripmime -i - -d $dir --name-by-type
cat $dir/text-html* | w3m -no-mouse -o display_link \
-o display_link_number -T text/html | \
sed 's!https*://.*!\x1B]8;;&\x1B\\&\x1B]8;;\x1B\\!g' | less -rX
rm -rf $dir
It’ll have to do.
With my Coronavirus-related CFT I finally got around to migrating off
Blogger. I lost comments, but I think I’ll probably keep it like that:
there’s twitter, and Blogger’s anti-spam facilities were pretty much
hopeless.
My first attempt used jekyll. I
suppose this works best with Github Pages, because I gave up on it
pretty quickly: various irritating Ruby version incompatibilities,
random tracebacks from modules, import not working well at all etc.
Next stop was hugo which was much, much
nicer. Although it was still a little tedious to import (there’s not
really integration, so you need 3rd party tools like the one I used
to import the Blogger content -
blog2md).
The base theme I ended up using was Strange
Case. Having battled with
impenetrable Wordpress themes in the past, it was refreshing to be able
to modify something so eminently hackable, and being based on the
familiar bootstrap was a big plus as well.
It took me a while to fix up a few things (like making Recent Posts
show only posts, instead of all pages), and getting used to the way
hugo searches the layout files took a bit of time, but it was all in all
a good experience.
It seemed a little tricky to create all the necessary 301 Redirect
directives for the old Blogger-style permalinks, so I crapped out and
just manually added a few that I know people might actually want to find
via Google.
I spent far too long trying to find an Atom feed importer for my old
Sun blog.
Seems like there isn’t a general one, so I threw
roller2hugo together instead,
which works just enough.
I’m the old-fashioned type who still likes getting email: I can process
it at my leisure while still handling high volume. Unfortunately github
itself can’t email you when commits are made to a particular repo
(unless you own it and can configure hooks). So I need to resort to the
atom feeds, and rss2email:
$ r2e new [email protected]
$ vi .rss2email/config.py
# set local (sendmail) delivery, disable HTML mail, etc.
$ r2e opmlimport subscriptions.xml
$ declare -f github-commits
github-commits ()
{
r2e add $(basename $1) "https://github.com/$1/commits/master.atom"
}
$ crontab -l | grep r2e
*/10 * * * * r2e run
$ tail -3 .procmailrc
:0
* User-Agent: rss2email
commits/
So every 10 minutes, we’ll get new commits from all the watched repos,
and procmail them into a commits
folder.
With the number of repos I’m watching, I have to set:
same-server-fetch-interval = 0.5
in the configuration to stop github throwing back 429 Too Many Requests
at me.
Private repositories
It’s pretty ghetto, but if you look at the source for
https://github.com/me/privaterepo/commits/master
, you’ll find an Atom
link including a token that you can use for getting notifications from
private repos. At least you’re not handing it off to a third-party like
IFTT with the above approach…
I just published new version of
zoom-lomax. This is updated to use
the v2 Zoom API, as v1 is going away at some point.
I run this every night so I can catch up on any meetings outside of my
normal timezone the next day; it’s proven very useful for me.
Newer versions of Gerrit, somewhat insanely, lack the old “Open All”
button to open each file in its own tab. Here’s a bookmarklet that does
so:
javascript: (
function() {
var dl = document.querySelectorAll(".pathLink");
if (!dl.length) {
dl = document.querySelectorAll("a.gr-file-list");
}
if (!dl.length) {
dl = document.querySelectorAll(".path");
}
if (!dl.length) {
dl = document.querySelectorAll(".com-google-gerrit-client-change-FileTable-FileTableCss-pathColumn > a");
}
if (!dl.length) {
dl = document.querySelector('body > gr-app')
.shadowRoot.querySelector('gr-app-element')
.shadowRoot.querySelector('gr-change-view')
.shadowRoot.querySelector('gr-file-list')
.shadowRoot.querySelectorAll('.pathLink');
}
if (!dl.length) {
alert('no links');
} else {
if (confirm('Open ' + dl.length + ' links in new windows?')) {
for (var i = 0; i < dl.length; ++i) {
window.open(dl[i].href);
}
}
}
}
)();
(Add the above as the “Location” of a bookmark.) If somebody knows a
less shitty way to traverse all the new shadow roots, I’d love to hear
it.
- 2021-01-27: updated to fix a javascript error
- 2021-02-09: updated for some other gerrit versions
- 2021-06-17: updated for yet another gerrit version
I found it a little bit non-obvious how to use
NAPI to add an external NIC to
a compute node so it can reach the external network rather than just the
internal admin
one.
We need to first tag the underlying physical NIC on the compute node
with the external
NIC tag. We need to look up the MAC of the physical
NIC:
computenode# # dladm show-phys -m ixgbe0
LINK SLOT ADDRESS INUSE CLIENT
ixgbe0 primary e4:11:5b:97:83:49 yes ixgbe0
then tell NAPI (from the headnode) that this NIC is going to provide the
external
tag:
sdc-napi /nics/e4:11:5b:97:83:49 -X PUT -d '{ "nic_tags_provided" : "external" }'
We now need to actually add the external
VNIC in NAPI:
cn=*your compute node UUID from `sdc-server list`*
ip=*IP address to use on external network*
vlan_id=*vlan id if any*
owner=$(sdc-useradm get admin | json uuid)
sdc-napi /nics -X POST -d @- <<EOF
{
"owner_uuid": "$owner",
"belongs_to_type": "server",
"belongs_to_uuid": "$cn",
"cn_uuid": "$cn",
"ip": "$ip",
"vlan_id": "$vlan_id",
"nic_tag": "external"
}
EOF
After a while, we should find that the DHCPD server has updated the
networking config file for the CN:
# cat /zones/$(vmadm list -Ho uuid alias=dhcpd0)/root/tftpboot/bootfs/e4115b978348/networking.json
...
"nictags": [
{
"mtu": 1500,
"name": "external",
"uuid": "86b73953-488a-4041-bd7a-83aa51c4ca22"
...
"vnics": [
...
"belongs_to_type": "server",
"nic_tag": "external",
...
And on rebooting the CN, we can find our interface up, and reachable
externally:
# ipadm show-addr external0/_a
ADDROBJ TYPE STATE ADDR
external0/_a static ok 192.168.0.44/24
With the advent of newboot in
SmartOS/Triton,
newly-installed systems will use loader
as the bootloader, replacing
grub
. See RFD
156 for some
technical background on the motivation of the switch.
It’s often the case that people want to make some modification to an
/etc
file in subsequent SmartOS boots. As we boot from ramdisk, we
can’t just directly modify the files. As originally described on
Keith’s
blog
the way to get around this problem involves specifying specific files to
over-ride the default.
Obviously this has changed under loader
.
NOTE: This is now documented at on the SmartOS wiki at
Modifying Boot Files.
Please look there instead, as the below may not stay current.
Let’s presume we want to over-ride /etc/system
to set kmem_flags
.
First, let’s take a copy of our file and edit it:
# sdc-usbkey mount
/mnt/usbkey
# mkdir -p /mnt/usbkey/bootfs/etc/ # or whatever
# cp /etc/system /mnt/usbkey/bootfs/etc/system # or /mnt/usbkey/bootfs/dtrace.conf etc.
# echo "set kmem_flags=0xf" >>/mnt/usbkey/bootfs/etc/system
Now we want loader
to prepare this file as a bootfs module. In grub,
we used something like
“module /bootfs/etc/system type=file name=etc/system
”. For loader,
it’s similar:
# cd /mnt/usbkey/boot
# grep etc_system loader.conf.local
etc_system_load=YES
etc_system_type=file
etc_system_name=/bootfs/etc/system
etc_system_flags="name=/etc/system"
The prefix (etc_system_
) is fairly arbitrary, though often named after
the module. For each file you want, you’d want a _load
, _type
,
_name
and _flag
line specified. The _name
entry is the path to the
file for loader to use; the name
flag is the /system/boot/...
path
you want the modified file to be available at after booting.
If this all worked OK, then we should see during boot something like:
Loading /os/20190207T125627Z/platform/i86pc/kernel/amd64/unix...
Loading /os/20190207T125627Z/platform/i86pc/amd64/boot_archive...
Loading /os/20190207T125627Z/platform/i86pc/amd64/boot_archive.hash...
Loading /bootfs/etc/system...
Booting...
SunOS Release 5.11 Version joyent_20190207T125627Z 64-bit
Copyright (c) 2010-2019, Joyent Inc. All rights reserved.
WARNING: High-overhead kmem debugging features enabled (kmem_flags = 0xf)...
And we should find a copy of our modified file here:
# tail /system/boot/etc/system
...
set kmem_flags=0xf
The kernel has a search path such that it will load from /system/boot
prior to /
. So the above is our active file, although /etc/system
is
still the standard shipped file.
Since Liferea in more recent versions requires a download manager (it
does not attempt to deal with the constant “new” podcast downloads on
broken RSS feeds), I tried a few different ones. None of them
worked. The best of a bad bunch was uGet, but that still often got stuck
on a busy loop, forgot where to download, failed to handle duplicates
etc.
I realised that in fact the best option was this marvellous piece of
engineering:
#!/bin/bash
url="$1"
readonly LOG_FILE="/var/tmp/download.log"
touch $LOG_FILE
exec 1>>$LOG_FILE
exec 2>&1
#set -x
if grep "$1" ~/.downloaded >/dev/null; then
echo "$(date): skipping $1"
exit 0
fi
echo "$(date): downloading $1"
echo "$1" >>~/.downloaded
cd $my_download_dir
curl -RksSLJO "$1"
Not exactly stunning but it works.