Unix: add a few unix notes

src/content/unix/email-with-curl.md

@@ -0,0 +1,116 @@
+---
+title: 'Send emails using Curl'
+description: 'Examples on how to automate emails with Curl'
+updateDate: 'Jul 08 2022'
+heroImage: '/curl-logo.webp'
+---
+
+# Emailing with Curl
+
+`curl` is an amazing networking tool. It can even automate sending emails!
+
+## Email just a file
+
+For most basic emails, we can stuff the headers into the email content file
+itself. Here's a basic example:
+
+```bash
+# This line writes the content to a file called email.txt.
+# Usually you should use a text editor to write to a file yourself.
+cat <<EMAIL > email.txt
+From: Emiliko Mirror <emiliko@cs.ox.ac.uk>
+To: Emiliko Mirror <emiliko@gmail.com>
+Subject: Sleep triggered on $(hostname)
+Date: $(date)
+
+Dear me,
+
+The system went to sleep! I thought I should notify my gmail account when it
+happened.
+
+cheers,
+Emiliko
+EMAIL
+
+# Sends the file called `email.txt` as an email, not an email attachment.
+# Note that you need to replace <my-password-here> with your gmail password.
+curl --silent --ssl-reqd \
+  --url 'smtps://smtp.gmail.com:465' \
+  --user 'emiliko@cs.ox.ac.uk:<my-password-here>' \
+  --mail-from 'emiliko@cs.ox.ac.uk' \
+  --mail-rcpt 'emiliko@gmail.com' \
+  --upload-file email.txt
+```
+
+The `From:` - `Date:` headers at the top are very important. Gmail seems to
+insert them automatically if they're missing, though other mail providers might
+not, so make sure to leave them in.
+
+If you use 2fa, you won't be able to use your account password to authenticate.
+Instead, you'll need to [obtain an app
+password](https://support.google.com/accounts/answer/185833?hl=en) for your
+account.
+
+## Email with attachments
+
+We can also `CC`, `BCC` and attach files with our curl emails.
+
+Attachments need a MIME type for the file, which is easiest obtained with the
+`file` command. In this example, we also remove the headers from the email file,
+opting to use the more explicit `-H` curl option.
+
+```bash
+# Setup variables for attachment file. Not necessary but much cleaner
+declare -r attach_file=mirrors_house.png
+declare -r mime_type="$(file --mime-type "$attach_file" | sed 's/.*: //')"
+
+# Fill a file called `email.txt` with the email content
+cat <<EMAIL > email.txt
+Dear classmates,
+
+I just bought a new house! Check out the picture I attached below
+
+OMGOMGOMG, I'm so excited!
+
+cheers,
+Kate Mirror
+EMAIL
+
+# Sends email.txt as the email content and attaches mirrors_house.png
+curl --silent --ssl-reqd \
+  --url 'smtps://smtp.fastmail.com:465' \
+  --user 'kate%40mirror.house:<my-password>' \
+  --mail-from "kate@mirror.house" \
+  --mail-rcpt 'emiliko@cs.ox.ac.uk' \
+  --mail-rcpt 'lou@lou.me' \
+  --mail-rcpt 'louis@louis.me' \
+  -F '=(;type=multipart/mixed' \
+  -F "=$(cat email.txt);type=text/plain" \
+  -F "file=@${attach_file};filename=home.png;type=${mime_type};encoder=base64" \
+  -F '=)' \
+  -H "From: Kate Mirror <kate@mirror.house>" \
+  -H "Subject: Check out my new place!" \
+  -H "To: Emiliko Mirror <emiliko@cs.ox.ac.uk>" \
+  -H "CC: Lou Mirror <lou@lou.me>" \
+  -H "Date: $(date)"
+```
+
+Notice that for `BCC` the user isn't mentioned in `-H` at all, though you'll
+still need a `--mail-rcpt` line for them.
+
+Oddly, some mail servers seem sensitive to the filename field. My university
+server would consistently bounce emails when I tried to have a filename field.
+Consider removing it to use the file's actual name. In the example above, we'd
+use `mirrors_house.png` instead of `home.png`.
+
+### Further reading
+
+ - [A basic official guide](https://everything.curl.dev/usingcurl/smtp)
+ - [Sending a simple email with
+   curl](https://stackoverflow.com/questions/14722556/using-curl-to-send-email)
+ - [An example on using the -F option with
+   curl](https://blog.ambor.com/2021/08/using-curl-to-send-e-mail-with.html)
+ - [Backup of the above on
+   github](https://github.com/ambanmba/send-ses/blob/main/send-ses.sh)
+ - [A hint at using the filename field in
+   forums](https://stackoverflow.com/questions/15127732/change-name-of-upload-file-in-curl)

src/content/unix/ssh.md

@@ -1,8 +1,7 @@
 ---
 title: 'SSH Quick Start Guide'
 description: 'The fastest way to get all the SSH essentials out of the way'
-pubDate: 'December 26 2023'
+updateDate: 'December 26 2023'
-heroImage: '/blog-placeholder-3.jpg'
 ---
 
 # SSH