To set up resolvconf, the name server information handler (that's what the Synaptic package manager calls it):

      # need to sudo the following steps
      # install resolvconf, using Synaptic or apt-get
      rm /etc/resolv.conf # on my system, was a link to ../run/resolvconf/resolv.conf
      ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
      resolvconf -u
      # may need to restart networking
    

Note that with Linux Mint 21, the systemd-resolve command has been renamed to resolvectl.

To restart Cinnamon without logging out (don't know if this works with MATE):

      Atl-F2 (brings up dialog)
      r<return>
    

To list the hardware that is installed:

      sudo inxi -F
    

To see what version of Linux Mint is installed:

      cat /etc/os-release
    

To reload the /etc/exports file:

      sudo exportfs -ra
    

To see what is currently being NFS exported:

      sudo exportfs -s
    

To convert avi files with vorbis video:

      ffmpeg -i file.avi -vcodec h264 -an file.h264
      ffmpeg -i file.avi -acodec libfaac file.aac
      mp4box -add file.h264 -add file.aac file.mp4
    

To get a vob file from a DVD (dvd://1 means title 1):

      mplayer dvd://1 -dvd-device /path/to/dvd/folder -v -dumpstream -dumpfile movie.vob
    

To restore a postgres cluster from a pg_dumpall --clean command:

      psql --user postgres -f <dumpfile> postgres
    

Cron jobs for me and root:

      30 01 * * * /home/username/bin/backup.sh (me)
      00 01 * * * sh /home/username/bin/sys-backup.sh (root - perhaps just run manually)
    

I found the following technique on this page on stackoverflow.com. To concatenate two (or more) mp4 files that have the same encoding parameters, create a text file that lists them, one per line, like so:

      file 'video1.mp4'
      file 'video2.mp4'
    

then issue the following command:

      ffmpeg -f concat -safe 0 -i listfile -c copy output.mp4
    

To add metadata (i.e., chapters) to an mp4 file with ffmpeg, do this (the -map 0 is needed to prevent the subtitles from being removed):

      ffmpeg -i input.mp4 -f ffmetadata -i metadata.txt -map_metadata 1 -map 0 -codec copy output.mp4
    

Note: older versions of ffmpeg may not require the -f ffmetadata option.

To show the volume of an audio file:

      ffmpeg -hide_banner -i input.mp4 -af volumedetect -f null -
    

On Amazon, Lewis Balentine wrote a review of the PNY Quadro P400 graphics card that includes the following command for doing a hardware encoding of a ts video file ($f is the ts file):

      ffmpeg -hwaccel cuvid -i "$f" -vcodec h264_nvenc -profile:v 2 -g 30 -qp 26 -c:a ac3 "${f%.ts}.mp4"
    

This page on Tom's Hardware shows the following command:

      ffmpeg -i [source] -c:v [h264/hevc/av1]_nvenc -b:v [bitrate] -y [output]
    

To have bash insert the contents of a file into the command line, use this syntax: $(<file).

This link tells how to make the ls command revert to traditional behavior, and not put quotes around file names with spaces, namely by setting the following environment variable: QUOTING_STYLE=literal

To make Linux Mint boot in non-graphical mode, do the following:

      sudo systemctl set-default multi-user.target
    

To revert back, use graphical.target instead of multi-user.target. To see the current value, do:

      sudo systemctl get-default
    

To prevent Linux Mint from repeatedly adding printers, turn off the cups-browsed service. Note that when I did this and restarted, I no longer had printers, so I had to re-enable and start the service.

      sudo systemctl stop cups-browsed
      sudo systemctl disable cups-browsed
    

To get individual tracks from a flac file that has an entire album (assuming there is a cue file), do

      abcde -d x.flac
    

To force the displays to sleep, do

      sleep 3 && xset dpms force off
    

The sleep is necessary so lifting the key doesn't wake up the monitor.

To use sox to trim an audio file, do

      sox inputfile outputfile trim start duration
    

The start time is either a floating point number representing seconds, or a time of the format hh:mm:ss.sss. The duration can be specified using the same syntax. Prefixing the duration with a plus sign means from the beginning, prefixing with a minus sing means from the end, and prefixing with an equals sign means an absolute point in the file.

To use sox to normalize an audio file, do

      sox inputfile outputfile norm -3
    

The -3 is to avoid clipping. To get stats from a file, do

      sox inputfile -n stat