blog.gladis.org
about linux, python and stuff ...
[2020-10-22] Trigger build after file change
Install the inotify-tools, for example with yay:
yay -S inotify-tools
Then you can trigger a sphix build after a file change in docs
while true;
inotifywait -e close_write -r docs/;
make dirhtml;
end
Or to start the love2d game, but only when a lua file changes.
while true;
inotifywait -e close_write -r --include ".*\.lua" . ;
love .;
end
The inotifywait command waits until a file is updated, in our examples until a file handle is closed after a write.
[2018-05-07] Clean pacman package cache automatically in archlinux
To clean up the pacman package cache once you can run:
# paccache -rk2
This will remove all cached packages but keep the 2 versions of any installed one. The arch docu has more useful information.
# mkdir -p /etc/pacman.d/hooks/
# vim /etc/pacman.d/hooks/remove_old_cache.hook
and fill in the following
[Trigger]
Operation = Remove
Operation = Install
Operation = Upgrade
Type = Package
Target = *
[Action]
Description = Keep the last cache and the currently installed.
When = PostTransaction
Exec = /usr/bin/paccache -rvk2
I read about this solution in the arch formus
When you update your system you can see that the hook is running. Your output should be similar to this:
# pacman -Syu
...
( 8/13) Keep the last cache and the currently installed.
removed '/var/cache/pacman/pkg/lib32-glibc-2.26-11-x86_64.pkg.tar.xz'
removed '/var/cache/pacman/pkg/linux-headers-4.16.5-1-x86_64.pkg.tar.xz'
removed '/var/cache/pacman/pkg/glibc-2.26-11-x86_64.pkg.tar.xz'
removed '/var/cache/pacman/pkg/gcc-7.3.1+20180312-2-x86_64.pkg.tar.xz'
[2018-01-05] How to fix an expired gpg key to be able to run a system update on arch linux again
When I run my first update in the new year, I had the problem that one of the gpg keys expired, and I couldn't update my system.
$ sudo pacman -Syyu
error: pkgbuilder: signature from "Chris Warrick <kwpolska@gmail.com>" is unknown trust
:: Synchronizing package databases...
core 126.8 KiB 1527K/s 00:00 [#############################################################################] 100%
extra 1639.8 KiB 10.0M/s 00:00 [#############################################################################] 100%
community 4.3 MiB 18.0M/s 00:00 [#############################################################################] 100%
multilib 168.6 KiB 23.5M/s 00:00 [#############################################################################] 100%
pkgbuilder 846.0 B 0.00B/s 00:00 [#############################################################################] 100%
pkgbuilder.sig 310.0 B 0.00B/s 00:00 [#############################################################################] 100%
error: pkgbuilder: signature from "Chris Warrick <kwpolska@gmail.com>" is unknown trust
error: failed to update pkgbuilder (invalid or corrupted database (PGP signature))
sublime-text 1080.0 B 0.00B/s 00:00 [#############################################################################] 100%
sublime-text.sig 543.0 B 0.00B/s 00:00 [#############################################################################] 100%
error: database 'pkgbuilder' is not valid (invalid or corrupted database (PGP signature))
The solution was to refresh all keys with
$ sudo pacman-key --refresh-keys
[2017-10-08] fixed netctl connection problem
Since a while i couldn't connect via netctl to a wireless network. But since a manual connect like this worked:
wpa_supplicant -B -i wlp4s0 -c <(wpa_passphrase "my_ssid" "mypassword")
I didn't bother too much. Today I read through the documentaion again and found a suggestion if the connection fails.
I added this line manually to /etc/netctl/my_profile_name
ForceConnect=yes
And a sudo netcl start home was successful \o/ I removed the line again and it still woks, strange but who cares.
[2017-08-04] kill blocking or frozen ssh connection
I googled so many times now for this combination, so add it here for future reference.
Too kill a frozen ssh connection, hit those 3 keys after another.
[ENTER] [`] [.]
[2017-05-24] mount an encrypted partition in a terminal
Here is a way to mount a encrypted partition that was created with gnome-disks on a system without gnome from the commandline.
$ udisksctl unlock --block-device /dev/sda3
$ udisksctl mount --block-device /dev/mapper/luks-3c6da966-4101-470f-b7e5-cb385f93fd1f
[2017-02-01] run pygame for python3 in docker
To run Xorg application in docker you just need to mount the Xorg socket into the container. First you need to disable access control so that the app from inside the container can connect to the Xorg socket with xhost +
After that you can run the container and mount the socket:
docker run -it --rm -v /tmp/.X11-unix:/tmp/.X11-unix -v $PWD:/home -e DISPLAY=unix$DISPLAY \
--device /dev/snd --name pygame3 olafgladis/python3-pygame python3 /home/app.py
The important part is -v /tmp/.X11-unix:/tmp/.X11-unix. If you want to write your pygame application in python3 you don't have to compile pygame yourself, and just use this docker container. The Dockerfile for it can be found here. For the a small demo I provided also a small snake app and a bash script to start in inside the container.
Afaik this will only work on linux.
[2016-09-03] A process pool in python
When you need to spawn a lot of processes, so many that you don't want to spawn them at the same time this PopenPool can help you.
def run(self,):
while self.running_tasks or self.upcomming_tasks:
while self.upcomming_tasks and len(self.running_tasks) < self.pool_size:
self.consume_task()
still_running_tasks = deque()
while self.running_tasks:
task = self.running_tasks.popleft()
if task.poll() is None:
# task is not finished yet
still_running_tasks.append(task)
else:
self.finished_tasks.append(task)
self.running_tasks = still_running_tasks
This code will spawn the maximum number of processes and as soon one of them finishes the next one is spawned.
The full source can be found here
[2016-08-25] Access shell script variables from python
In case you want to read bash variables from python, I have an example for you. The method is not safe, it will execute the shell script, so you have to trust the input! But the nice part is, that even calculated variables are returned.
Here the interesting part:
def load_config(config_filename):
# to get the same set of env variables, we need to execute also multiple statements in one line
default_env = check_output_shell("true;set").decode('utf8')
config_data_list = open(config_filename).read().splitlines()
config_data_list.append("set")
# we join the lines with ; so the the BASH_EXECUTION_STRING will not contain newlines
config_env_list = check_output_shell(";".join(config_data_list)).decode('utf8').splitlines()
return dict(_get_dict_tuples(l) for l in config_env_list
if l not in default_env and not l.startswith('BASH_EXECUTION_STRING'))
The key is, to append a set to the shell file and execute it and compare the output to an empty shell script with a set in it. Here is an example with string concatination:
$ cat input/string_concatenation.conf
foo=bar
foo+=' baba'
$ python read-shell-vars.py input/string_concatenation.conf
{'foo': 'bar baba'}
And one with a list concatination:
$ cat input/list_concatenation.conf
lista=(a b c)
listb=(c d e)
listc=("${lista[@]}" "${listb[@]}")
$ python read-shell-vars.py input/list_concatenation.conf
{'lista': ['a', 'b', 'c'],
'listb': ['c', 'd', 'e'],
'listc': ['a', 'b', 'c', 'c', 'd', 'e']}
This will only work for config like shell scripts that will not print to stdout. If you need to support this you need to redirect the output of both set commands to a file and read them.
[2016-08-13] Hello Lektor
I switched my blog from jekyll to lektor. The transition was smooth and things like the tag cloud didn't need a hack in the first place. You can check out the sources at gitlab