Add lockmute post

content/System Administration/gnome-mute-when-locked.md

+Title: Mute speakers when locking your PC
+Description: Automatically mute audio output when your computer is locked.
+Date: November 1, 2019
+
+
+<center>![lockmute icon](/media/lockmute-250.png)</center>
+
+Are your coworkers/cohabitants tired of hearing notifications and other noises from your unattended computer?
+Use this script to automatically mute your speakers whenever the machine is locked, and un-mute when you return.
+
+* Tested with **GNOME 3.30** on **Debian 10**.
+* Mutes when locking, un-mutes when unlocking.
+* *Does not* un-mute if mute was enabled prior to locking the screen.
+
+### How it works
+
+* Watches `org.freedesktop.login1` for `LockedHint` events via `gdbus monitor`.
+* Uses `amixer` ([ALSA](https://www.alsa-project.org/wiki/Main_Page)) to mute/unmute.
+
+```bash
+#!/bin/bash
+
+# lockmute.sh - Mute sound output while GNOME is locked.
+
+STATE_FILE=~/.lockmute_state
+gdbus monitor -y -d org.freedesktop.login1 |
+    while read -r DBUS_OUTPUT ; do
+        LOCK_STATE=$(echo "$DBUS_OUTPUT" |
+                     grep -o "'LockedHint': <\w*>" |
+                     awk '{print $2}')
+        if [[ "$LOCK_STATE" == "<true>" ]]; then
+            AUDIO_STATE=$(amixer get Master |
+                          grep -o '\[\(on\|off\)\]')
+            if [[ "$AUDIO_STATE" == *"[off]"* ]]; then
+                echo "WAS_MUTED" > "$STATE_FILE"
+            else
+                echo "WAS_NOT_MUTED" > "$STATE_FILE"
+            fi
+            amixer set Master mute > /dev/null
+        elif [[ "$LOCK_STATE" == "<false>" ]]; then
+            if [[ "$(cat "$STATE_FILE")" == "WAS_NOT_MUTED" ]]; then
+                amixer set Master unmute > /dev/null
+            fi
+            rm "$STATE_FILE"
+        fi
+    done
+```
+
+
+## Installation
+
+1. Save to `/usr/local/bin/lockmute.sh`.
+2. Make it executable: `chmod +x /usr/local/bin/lockmute.sh`.
+
+## Test it
+
+You can test it by running `lockmute.sh` in a terminal. Play some music, and lock the screen (`Super`+`L`).
+
+## Run it automatically
+
+To run this anytime you're logged in, create an [autostart](https://developer.gnome.org/autostart-spec/) entry.
+
+### ```~/.config/autostart/lockmute.desktop ```
+
+```
+[Desktop Entry]
+Name=lockmute
+Exec=/usr/local/bin/lockmute.sh
+Type=Application
+NoDisplay=true
+X-GNOME-Autostart-enabled=true
+```