less big rename

computery_stuff/bash.md

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+---
+author: Alvie Rahman
+date: \today
+title: Bash
+tags: [ linux, shell, programming ]
+---
+
+# `set` builtin[^gnuset]
+
+- `-e`--- exit a program if any program returns a non-zero error code (fails)
+
+[^gnuset]: https://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#The-Set-Builtin

computery_stuff/docker_nginx_lets_encrypt.md

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+---
+author: Alvie Rahman
+date: \today
+title: Setting Up Nginx and Let's Encrypt in Docker
+tags: [ linux, docker, programming ]
+---
+
+# Setting Up Nginx and Let's Encrypt in Docker
+
+This turned out to be way harder than I thought it would be.
+I tried to follow
+[this](https://pentacent.medium.com/nginx-and-lets-encrypt-with-docker-in-less-than-5-minutes-b4b8a60d3a71)
+post here but the `init-letsencrypt.sh` script didn't work for me.
+
+Most of the content here is from that post.
+
+## Create the necessary files
+
+### `docker-compose.yaml`
+
+Notice how `certbot`'s `entrypoint` field is commented out?
+Yeah, that's one of the things that tripped me up.
+When the autorenew entrypoint is specified, you can't perform one of the future steps.
+
+```yaml
+version: '3'
+
+services:
+  nginx:
+    image: nginx:1.15-alpine
+    ports:
+      - "80:80"
+      - "443:443"
+    volumes:
+      - ./data/nginx:/etc/nginx/conf.d
+      - ./data/certbot/conf:/etc/letsencrypt
+      - ./data/certbot/www:/var/www/certbot
+  certbot:
+    image: certbot/certbot
+    # entrypoint: "/bin/sh -c 'trap exit TERM; while :; do certbot renew; sleep 12h & wait $${!}; done;'"
+    volumes:
+      - ./data/certbot/conf:/etc/letsencrypt
+      - ./data/certbot/www:/var/www/certbot
+```
+
+### `data/nginx/app.conf`
+
+Again, things are commented out in this file.
+The SSL section is commented out as Nginx cannot start an SSL server without first having SSL
+certificates but certbot won't give us SSL certificates unless we have a webserver (the certbot
+Docker image supports hosting a standalone server for this purpose but that would mean changing
+around the ports in `docker-compose.yaml`).
+
+Also the 301 redirect in the port 80 section is commented out as we don't want to immediately
+redirect certbot to a https URL we aren't listening for.
+
+```
+server {
+    listen 80;
+    server_name DOMAIN.NAME;
+
+    location /.well-known/acme-challenge/ {
+        root /var/www/certbot;
+    }
+
+    location / {
+        #return 301 https://$host$request_uri;
+        proxy_pass http://example.com;
+    }    
+}
+
+# server {
+#     listen 443 ssl;
+#     server_name DOMAIN.NAME;
+#     
+#     location / {
+#         # anything you want can go in here, of course
+#         proxy_pass http://example.com;
+#     }
+#     ssl_certificate /etc/letsencrypt/live/DOMAIN.NAME/fullchain.pem;
+#     ssl_certificate_key /etc/letsencrypt/live/DOMAIN.NAME/privkey.pem;
+#     include /etc/letsencrypt/options-ssl-nginx.conf;
+#     ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
+# }
+```
+
+## Set your domain
+
+Run the following command, replacing `REPLACEME` with your domain name:
+
+```
+sed -i 's/DOMAIN.NAME/REPLACEME/g' data/nginx/app.conf
+```
+
+## Get your first certificates
+
+Run the following commands:
+
+    docker-compose up -d nginx
+    docker-compose run certbot certonly --webroot /var/www/certbot
+
+Enter the information your are prompted for.
+
+## Enable HTTPS on Nginx and auto renew certificates
+
+1. Uncomment the commented out server block in `data/nginx/app.conf`.
+2. Remove the `proxy_pass` line in the port 80 server block.
+3. Uncomment the line starting with `return 301`
+4. Restart Nginx (`docker-compose restart nginx`)
+5. Uncomment line beginning with `entrypoint` in `docker-compose.yaml`

computery_stuff/git.md

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+---
+author: Alvie Rahman
+date: \today
+title: Git
+tags: [ linux, programming, git ]
+---
+
+
+# Fix detached head
+
+From <https://stackoverflow.com/a/10229202>:
+
+## To Delete Changes
+
+```
+git checkout main
+```
+
+## To Keep Changes
+
+```
+git branch temp
+git checkout main
+git pull . temp
+git branch -D temp
+```
+
+# Retroactively Sign Commits
+
+From <https://webdevstudios.com/2020/05/26/retroactively-sign-git-commits/>:
+
+1.
+   ```
+   git rebase -i HEAD~<number of commits to sign>
+   ```
+
+2. Replace `pick` with `reword`:
+
+   In vim: `:%s/^pick/reword/:wq`
+
+3. Save all commit messages
+4. Force push to remote

computery_stuff/gnome.md

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+---
+author: Alvie Rahman
+date: \today
+title: GNOME is a Whole Mess
+tags: [ gnome, linux, troubleshooting ]
+---
+
+Gnome is, like, a whole mess. These are the weird issues I had to solve.
+
+# Super+1, Super+2, Super+3, etc. keys can not be remapped in Gnome (gnome super+1 shortcut not working)
+
+From <https://unix.stackexchange.com/a/510376>:
+
+> It turns out that some keyboard shortcuts in Gnome do not show up in Settings → Devices →
+> Keyboard → Keyboard Shortcuts. These "hidden" shortcuts are accessible by using the dconf-editor
+> command. In the dconf editor, the Super+1 remapping was found at
+> 
+>     org/gnome/shell/keybindings/switch-to-application-1
+
+# Setting Default Terminal
+
+Not possible??
+
+# No Bluetooth Dongle not Recocgnised
+
+Had to update BIOS.

computery_stuff/go.md

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+---
+author: Alvie Rahman
+date: \today
+title: Go (golang)
+tags: [ golang, programming ]
+---
+
+# Getting Up to Speed With Go
+
+Probably the most useful resoure I found was the [Tour of Go](https://tour.golang.org/).
+It's easy to understand and teaches you all you need to know.
+
+# `godoc` [^golang-godoc]
+
+> Godoc parses Go source code - including comments - and produces documentation as HTML or plain
+> text.
+> The end result is documentation tightly coupled with the code it documents.
+> For example, through godoc's web interface [which is at <http://localhost:6060> by default] you
+> can navigate from a function's documentation to its implementation with one click.
+
+## Installing godoc // `command not found: godoc`
+
+```bash
+go get golang.org/x/tools/cmd/godoc
+```
+
+# `go.mod`
+
+## `replace` [^go-mod-edit]
+
+```
+go mod edit -replace old.repo/location=../new/location
+```
+
+or 
+
+```
+echo "old.repo/location => ../new/location" >> go.mod
+```
+
+> The `-replace=old[@v]=new[@v]` flag adds a replacement of the given
+> module path and version pair. If the @v in old@v is omitted, a
+> replacement without a version on the left side is added, which applies
+> to all versions of the old module path. If the @v in new@v is omitted,
+> the new path should be a local module root directory, not a module
+> path. Note that -replace overrides any redundant replacements for old[@v],
+> so omitting @v will drop existing replacements for specific versions
+
+[^golang-godoc]: Andrew Gerrand, 31 March 2011 --- <https://blog.golang.org/godoc>
+[^go-mod-edit]: <https://golang.org/ref/mod#go-mod-edit>

computery_stuff/libvirt.md

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+---
+author: Alvie Rahman
+date: \today
+title: libvirt
+tags: [ linux, virtualisation ]
+---
+
+# issues
+
+## default network is not running
+
+```bash
+# virsh net-start default
+```
+
+## `no polkit agent available to authenticate action 'org.libvirt.unix.manage'`
+
+add user to `libvirt` group
+
+```bash
+usermod -a -G libvirt user
+```

computery_stuff/linux.md

@@ -0,0 +1,20 @@
+---
+author: Alvie Rahman
+date: \today
+title: Linux
+tags: [ linux ]
+---
+
+# user stuff
+
+## add user to group
+
+```bash
+usermod -a -G group user
+```
+
+## change primary user group
+
+```bash
+usermod -g group user
+```

computery_stuff/postgres.md

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+---
+author: Alvie Rahman
+date: \today
+title: Postgres
+tags: [ programming ]
+---
+
+\tableofcontents
+
+# Chapter 24: Backup and Restore[^c24]
+
+Three types of backups:
+
+- SQL dump---create text file of SQL commands that can recreate the database
+
+   `pg_dump dbname > outfile`
+
+   To restore: `psql dbname < infile`
+
+   - must be run as database superuser
+   - can be run remotely
+   - set host and username with `-h` and `-U` switches
+
+- File system level backup
+
+   `tar -cf backup.tar /usr/local/pgsql/data`
+
+   - The database server **must** be shut down
+   - You can only backup and restore entire database clusters
+
+- Continuous archiving (write ahead log archiving)
+
+   - "We do not need a perfectly consistent file system backup as the starting point."
+   - method can be used to create a continuous backup
+   - supports point in time recovery
+   - can be used to create a warm standby system
+
+   - can only be used to restore an entire database cluster
+   - requires a lot of archival storage
+
+## SQL Dump
+
+### Restoring a dump
+
+Important note before you restore a database:
+
+> Before restoring an SQL dump, all the users who own objects or were granted permissions on objects
+  in the dumped database must already exist. If they do not, the restore will fail to recreate the
+  objects with the original ownership and/or permissions. (Sometimes this is what you want, but
+  usually it is not.)
+
+You should probably read the whole document [here](https://www.postgresql.org/docs/9.1/backup-dump.html)
+
+## File system backup
+
+You can run a FS level backup with minimal downtime with `rsync`:
+
+1. Perform a backup with `rsync` while system is live
+2. Shut down database server
+3. Rerun `rsync` backup command
+4. Restart database server
+
+The second `rsync` command will run significantly quicker as it only has to transfer what has
+changed since the first backup.
+
+## Write Ahead Log (WAL) archiving
+
+- WAL segment files usually get "recycled" by being renamed
+- to archive WAL data, the content of each segment is captured and saved before it is reused
+
+   - you can save the data any way you like
+
+- to enable WAL archiving:
+
+   1. set `wal_level` to `replica` or higher
+   1. set `archive_mode` to `on`
+   1. set `archive_command` to the command to use to backup
+
+      - e.g.
+
+         ```
+         archive_command = 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'  # Unix
+         archive_command = 'copy "%p" "C:\\server\\archivedir\\%f"'  # Windows
+         ```
+
+         where `%f` is the filename of the file to archive and `%p` is the path of file to archive:
+
+         ```
+         test ! -f /mnt/server/archivedir/00000001000000A900000065 && cp pg_xlog/00000001000000A900000065 /mnt/server/archivedir/00000001000000A900000065
+         ```
+
+      - The command must only ever return a exit status of 0 **only if it succeeds*
+
+         - postgres will recycle the file if the command returns 0
+
+      - The archived data should have minimal access permissions
+      - the archive command should generally refuse to overwrite files and return non-zero
+      - In writing your archive command, you should assume that the file names to be archived can be
+        up to 64 characters long and can contain any combination of ASCII letters, digits, and dots.
+      - It is not necessary to preserve the original relative path (`%p`) but it is necessary to
+        preserve the file name (`%f`).
+   
+   1. make a base backup
+
+### make a base backup[^pg_basebackup]
+
+1. ensure that WAL archiving is working and set up properly.
+1. Run `pg_basebackup -D - -F tar > backup.tar`
+
+
+[^c24]: https://www.postgresql.org/docs/9.1/backup-dump.html
+[^pg_basebackup]: https://www.postgresql.org/docs/13/app-pgbasebackup.html

computery_stuff/pulseaudio.md

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+---
+author: Alvie Rahman
+date: \today
+title: Pulseaudio
+tags: [ pulseaudio, linux, audio, mixing, microphone, sink ]
+---
+
+# Collect and Mix Sound Input From Different Sources {#paMixer}
+
+## Create Mixer {#createMixer}
+
+From <https://askubuntu.com/a/870596>:
+
+> [...]
+>
+>     pactl load-module module-null-sink sink_name=inputs
+>
+> [...] please repeat this for [every] input you want to mix [...]
+>
+>     pactl load-module module-loopback sink=inputs
+>
+> Now you will have to connect this new "loopback" channels to the device you intend to record from.
+> You can do this using "pavucontrol" (install it if missing), open the "Recording" tab, select
+> "Virtual Streams" from the bottom selector and then make sure you connect a different input to
+> each different loopback.
+> [...]
+
+The number returned by each command is the module id.
+You may want to keep it if you want to [delete them individually](#destroyMixerSpecific).
+
+## Destroy Mixer {#destroyMixer}
+
+### Destroy _all_ Loopback and Null-Sink Modules {#destroyMixerAll}
+
+From <https://www.pclinuxos.com/forum/index.php/topic,119695.msg1159936.html#msg1159936>:
+
+>
+>     pactl unload-module module-loopback
+>     pactl unload-module module-null-sink
+>
+
+This will unload _all_ loopback and null-sink modules.
+
+### Destroy Specific Modules {#destsroyMixerSpecific}
+
+>
+>     pactl unload-module <module number>
+>

computery_stuff/python.md

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+---
+author: Alvie Rahman
+date: \today
+title: Python
+tags: [ docker, python, programming, io ]
+---
+
+# Issues
+
+## No log output when running in docker
+
+Change line beginning with `CMD` from:
+
+```Dockerfile
+CMD [ "python", "app.py" ]
+```
+
+to:
+
+```Dockerfile
+CMD [ "python", "-u", "app.py" ]
+```
+
+This disabled output buffering (stdout and stderr).
+