Blender, jupyter, TLS, ls, java

how_to

@@ -287,6 +287,10 @@ PDF :
         Master PDF Editor (free version):
             https://code-industry.net/free-pdf-editor/
             trizen -S masterpdfeditor
+    Decrypt pdf files:
+        # For example when pdftk spews this error:
+        # `Error: Invalid PDF: unknown.encryption.type.r`
+        qpdf --decrypt input.pdf output.pdf
 
 D-Bus :
     To reload service files /usr/share/dbus-1/services/
@@ -321,8 +325,20 @@ Drag & drop files:
 
 Fix hardware clock (with chrony / NTC):
     sudo chronyc
+        # Diagnose
+        activity
+        sources
+        tracking
+
+        # Bring NTP online
+        online
+
+        # Force step
         makestep
+
+        # Synchronize hardware clock with system clock
         trimrtc
+
         quit
     Alternative to trimrtc:
         sudo hwclock --systohc
@@ -434,6 +450,28 @@ Video and audio editing:
             Your text here                  # Actual text
                                             # Mandatory empty line
         ffmpeg -i in.mp4 -vf "scale=512:-2:flags=lanczos,split[x][z];[z]palettegen[y];[x][y]paletteuse,subtitles=text.srt:force_style='FontName=Oswald,Fontsize=80,FontWeight=Bold'" -r 10 out.gif
+    mp3 to video:
+        # https://shkspr.mobi/blog/2020/02/posting-audio-to-twitter/"
+        # Waveform
+        ffmpeg \
+            -i input.mp3 \
+            -filter_complex "[0:a]showwaves=s=640x480:mode=line,format=yuv420p[v]" \
+            -map "[v]" \
+            -map 0:a \
+            -c:v libx264 \
+            -c:a copy \
+            out.mkv
+        # Still image
+        ffmpeg \
+            -loop 1 \
+            -i image.jpg \
+            -i audio.mp3 \
+            -c:v libx264 \
+            -tune stillimage \
+            -c:a copy \
+            -pix_fmt yuv420p \
+            -shortest \
+            out.mp4
 
 ImageMagick:
     crop to aspect ratio
@@ -1105,6 +1143,7 @@ Mounting .bin/.cue image files:
 Manual IMAP connection:
     # https://www.atmail.com/blog/imap-101-manual-imap-sessions/
     # https://stackoverflow.com/questions/14959461/how-to-talk-to-imap-server-in-shell-via-openssl
+    # https://gist.github.com/fedir/1d8f8fb8a5f80090705ef7793936216a²
 
     $ openssl s_client -connect <imap server>:993 -crlf [-quiet]
     $ openssl s_client -connect <imap server>:143 -crlf -starttls imap [-quiet]
@@ -1114,6 +1153,9 @@ Manual IMAP connection:
     A2 list "" "*"
     # list everything under a particular prefix
     A3 list "INBOX" "*"
+    # Or:
+    # (will print current UIDVALIDITY (useful for fixing mbsync))
+    A4 select inbox
     A99 logout
 
 gdb tricks:
@@ -1291,3 +1333,33 @@ Fix chromium microphone autogain (qutebrowser):
 
     # https://github.com/qutebrowser/qutebrowser/discussions/6628
     # https://bugs.chromium.org/p/chromium/issues/detail?id=435112
+
+Blender:
+    Display vertex indices (blender >= 2.8):
+        # https://blender.stackexchange.com/a/158495
+        # https://devtalk.blender.org/t/how-to-enable-the-vertex-indices-overlay-over-each-vertex/15491/4
+        - Edit > Preferences > Interface > Developer Extras (enable)
+        - Edit Mode
+        - Overlays (dropdown, top-right) > Indices (enable) (under: "Developer")
+
+Jupyter:
+    Clear notebook of output data for publishing:
+        # https://stackoverflow.com/a/47774393/5309963
+        # In-place version
+        jupyter nbconvert --clear-output --inplace my_notebook.ipynb
+        # Or to write to a new file
+        jupyter nbconvert --clear-output \
+            --to notebook --output=my_notebook_no_out my_notebook.ipynb
+
+Check SSL/TLS certificate expiration date:
+    echo | openssl s_client -servername <name.example.tld> -connect <example.tld>:443 2>/dev/null | openssl x509 -noout -dates
+
+List files in chronological order with ls:
+    # https://shkspr.mobi/blog/2020/12/anatomy-of-an-ls-command/
+    ls -trhgGN --color=always | cut -d" " -f3-
+
+Change default java environment (archlinux):
+    # https://wiki.archlinux.org/title/Java#List_compatible_Java_environments_installed
+    archlinux-java status
+    # Example
+    archlinux set java-18-openjdk