Added snap notes to the knowledge base

knowledge base/snap.md

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+# Snap
+
+## TL;DR
+
+```shell
+# Find snaps.
+snap find chezmoi
+snap find --private boincstats-js
+snap search vscode
+
+# View detailed information about snaps.
+snap info snapd
+
+# Download snaps and their assertions without installing them
+snap download constellation
+
+# Install snaps.
+sudo snap install karuta
+sudo snap install code-tray --channel=beta
+snap ack foo.assert && snap install foo.snap
+snap install --dangerous foo.snap
+snap install --devmode foo
+snap install --classic foo
+
+# List installed snaps.
+snap list
+snap list --all
+
+# Manually update snaps.
+sudo snap refresh
+sudo snap refresh awdur
+sudo snap refresh mist --channel=beta
+
+# Revert snaps to a prior version.
+sudo snap revert widl-nan
+sudo snap revert bunyan --revision 5
+
+# Remove snaps.
+sudo snap remove runjs
+
+# Remove all old revisions of all installed snaps.
+snap list --all \
+  | grep disabled | awk '{print $3, $1}' \
+  | xargs -I {} -t sh -c "sudo snap remove --purge --revision {}"
+
+# Log in/out to/from snap.
+sudo snap login
+snap logout
+
+# View transaction logs.
+snap changes
+snap change 123
+
+# Watch transactions.
+snap watch 123
+
+# Abort transactions.
+snap abort 123
+
+# View available snap interfaces.
+snap interfaces
+
+# Connect a plug to the ubuntu core slot.
+snap connect foo:camera :camera
+
+# Disconnect a plug from the ubuntu core slot.
+snap disconnect foo:camera
+
+# Disable snaps.
+snap disable foo
+
+# Enable snaps.
+snap enable foo
+
+# Set a snap's properties.
+snap set foo bar=10
+
+# Read a snap's current properties.
+snap get foo bar
+```
+
+## Manage revisions
+
+```shell
+# List installed snaps with all their revisions.
+snap list --all
+
+# Remove all old revisions of all installed snaps.
+snap list --all \
+  | grep disabled | awk '{print $3, $1}' \
+  | xargs -I {} -t sh -c "sudo snap remove --purge --revision {}"
+```
+
+## Further readings
+
+- [cheat.sh]
+- [Managing Ubuntu snaps]
+
+[cheat.sh]: https://cheat.sh/snap
+[managing ubuntu snaps]: https://www.freecodecamp.org/news/managing-ubuntu-snaps/