If you get this error message: can't read superblock on /dev/sde1
you can try to fix it by the following code sudo fsck -yv /dev/sde1.
normalize audio volume
In Linux you can
1) change physically the volume, recodifying the files
such as
- with ffmpeg-normalize, a tool for automatic changes
- or with ffmpeg, for manual changes (i.g.
ffmpeg -i input.mp3 -filter:a "loudnorm" -q:a 2 output.mp3for a change with a re-encodig of high quality, orffmpeg -i input.mp3 -filter:a "loudnorm" -b:a 192k output.mp3to a bitrate of 192, and so on)
2) modifying only the way your file is read (by the audioplayers)
- with normalize-audio, which don’t encode the files, but change only the volume metatag.
- or with mp3gain (
mp3gain -r *.mp3, ormp3gain -r -k *.mp3, to avoid clipping problem)
This second way on the one hand is less invasive (and less destructive), but on the other hand the changes could be not correctly read by the audio player you use.
calibre strange behavior
it may happen that keys left and right don’t work as expected, showing two columns instead of one. You can try to resize the window.
embed a playlist in a web page
After many attempts I finally figured taht it’s impossible embed an audio playlist (such as m3u) to a webpage: you can add only multiple (audio) files, but not a playlist.
I tried with the <audio> tag: nothing to to, even with jquery or javascript. Neither with <embed> or <object> html tags: html developers allow only a single audio playing, not a playlist.
The mimetype “audio/x-mpegurl” doesn’t work.
linux remove old kernels
Recently Ubuntu-based linux SO doesn’t remove automatically old kernels, with the command
sudo apt-get autoremove --purgeThis because kernels, even automatically installed, are considered manually installed, and so they are not automatically removed.
To solve this, you should do beforehand this command
sudo apt-mark auto $(apt-mark showmanual | grep -E "^linux-([[:alpha:]]+-)+[[:digit:].]+-[^-]+(|-.+)$")With this command you say that all kernels are automatically installed, and therefore the previuous command (sudo apt-get autoremove –purge) will work.
nvidia grafical card and linux kernel
It could happen that a new kernel doesn’t work with your nvidia (geforce) grafical card. The problem could de the linux-modules, such as linux-modules-nvidia-460-5.8.0-53-generic.
You can check it by the following command
dpkg --list | egrep -i --color 'linux-image|linux-headers|linux-modules' | awk '{ print $2 }'To solve this, if you find that the last kernel does’t have a matchintg nvidia module, you have to install manually that module
sudo apt-get install linux-modules-nvidia-460-5.8.0-53-genericimport an xml into phpmyadmin
Given that WordPress doesn’t allow to import a local file (and this is quite unfair, in my opinion), you can transform a wp site into a xml file and then import it in your local database via phpmyadmin.
But you have to format carefully the xml: look how phpmyadmin export an xml file and format your xml according to that model.
regex replace html tags
In exporting a odt file to epub LibreOffice can make many mistakes, such as get a 2nd level title not with <h2>, but with <p class=”para0″>. To fix this error, you can use regex, in this way:
find: <p class="para0">(.*?)</p>
replace: <h2>\1</h2>and so on for similar cases.
regex “whatever”
If you want to select “Whatever” (word or character), regardless of its length, you can simply use
(.*?)
For example if you want delete all the words between <span> and </span>, as in the following row
many words <span>many other words here</span> other words
you can use
delete <span>(.*?)</span>. The result will be:
many words other words
pdf outline
Pdfmod is very simple and powerful tool to add (as bookmarks) an outline (structure) to a pdf.