probing: pc0 com0 mem[636K 1887M 16M 84K 88K 752K 16K 4M 584K 7M 6M 6148M]
disk: hd0* hd1* hd2* hd3* hd4
>> OpenBSD/amd64 BOOTX64 3.69
boot>
cannot open tftp:/etc/random.seed: No such file or directory
booting tftp:/bsd: open tftp:/bsd: No such file or directory
 failed(2). will try /bsd

1. Home directory
2. Primary backup
3. Secondary backup

$ kubectl get svc -o wide registry
NAME       TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE     SELECTOR
registry   ClusterIP   None         <none>        5000/TCP   5d20h   app=registry

# ospfctl show rib
Destination          Nexthop           Path Type    Type      Cost    Uptime
192.168.0.4          192.168.2.4       Intra-Area   Router    20      04:47:00
192.168.2.0/24       192.168.2.3     C Intra-Area   Network   20      05:06:25
10.244.1.0/24        192.168.2.65      Type 2 ext   Network   20      04:16:00
10.244.2.0/24        192.168.2.66      Type 2 ext   Network   20      04:16:00
10.244.3.0/24        192.168.2.67      Type 2 ext   Network   20      04:16:00

To make name resolution work, we will configure a stub zone and port forwarding for DNS

$ traceroute -n registry.default.svc.mykube.lan
traceroute to registry.default.svc.mykube.lan (10.244.3.62), 64 hops max, 40 byte packets
1  192.168.0.7  11.875 ms  10.928 ms  11.47 ms
2  192.168.2.67  0.749 ms  0.483 ms  0.349 ms
3  10.244.3.62  0.459 ms  0.328 ms  0.383 ms

• The psql \crosstab command provides a quick way to reformat the output of an interactive query, but is of no use for applications.
• The crosstab functions from the contrib module are awkward to use since they take a query as input, and has limited means of customization.

But we can assemble these using aggregate functions or CTEs.

Perhaps the most interesting question is not how to implement IPv6 networking, but determining why anyone would need it. The 128-bit address space is divided into a strict hierarchy, and it may be that this allows the protocol to operate with less cooperation between geographic regions. If this is true, then maybe IPv6 is an alternative plan to keep the Internet up if individual countries sabotage IPv4 routing.

Program structure has three sections, all of which are optional

BEGIN { ... }
/patternN/ { ... }
END { ... }

1. ZFS is able to distribute data across multiple devices, and this format is portable. Unlike traditional RAID, only dataset records are copied, making recovery very efficient. ZFS does away with the need for a volume manager, so there are no platform-specific layers such as BSD disklabels, or LVM. (BTRFS also has these capabilities, but is Linux-only.)
2. Native encryption, which allows send/receive of datasets even without unlocking and mounting a volume.
3. By setting volmode raw block devices can be provisioned for virtual machines, or across the network by way of iSCSI.

JavaScript may be executed in the context of the headless browser, so any kind of change may be made to the page before taking a snapshot (PNG) or saving as a PDF.

If the partition key is also a natural key, such as a date, pruning may appear to work in all cases, but if an intermediate lookup is required (name → id), queries will resort to scan all partitions.

By using TFTP to pivot to a minroot, then switching to HTTP the entire process can be audited and tailored for individual hosts. This methodology aims to borrow techniques used by an automated install for OpenBSD and Red Hat Linux.

Note taking also services to keep long-term goals moving. On a daily basis write-ahead logging can provide short-term focus. By keeping a personal record of experiments is a reserve to draw on when the rest of the team will be most receptive to a change.

The organization for note-taking can a directory with plain text files, but a framework such as Sphynx provides a way to create personal notes that can be easily shared with a team.

In production, a high-performance and reliable hypervisor allows services to be provisioned and updated one at a time. This capability avoids the added risk and complexity of fork-lift upgrades.

Although Ubuntu is a derivative of Debian, it doesn't follow the same conventions for an automated install.

x86_64 hardware and hypervisors usually don't provide a means of picking a one-time boot device. To force a reinstall wipe the first part of the disk.

# reinstall
# use with caution!
dd if=/dev/zero of=/dev/sda bs=1M count=100
reboot

This concept developed after I noticed how many people were willing to take the time to write an email to point out typos, broken links or errors on this online journal and other project pages.

Keeping the length of the encoded string short is important to minimizing overhead, especially for cookies which are added to the header in every HTTP request.

This mode is available by setting the mode attribute of a JavaScript Request object. The following is an example using the Fetch API

async function sct_postData(url, data={}) {
  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    },
    mode: 'cors',
    body: JSON.stringify(data)
  });
  return response.json();
}

Specifying 'no-cors' does not mean relax the protocol, it means don't follow the protocol which might allow external resource.

Fortunately, a hosting provider such as Vultr can deliver an OpenBSD instance that can reinstall itself using and autoinstall answers file and disklabel fetched over HTTP.

# /etc/fstab
/dev/sd0a / ffs rw 1 1
/dev/sd0b none swap sw
/dev/sd0d /usr ffs rw,nodev 1 2
/dev/sd0e /usr/local ffs rw,wxallowed,nodev 1 2
/dev/sd0f /tmp ffs rw,nodev,nosuid 1 2
/dev/sd0g /home ffs rw,nodev,nosuid 1 2
/dev/sd0h /var ffs rw,nodev,nosuid 1 2

Using a pre-built cloud image as a trampoline also provides the opportunity to exclude some base filesets or include other capabilities using siteXX.tgz.

1. Databases frequently keep records based on the user who ran a task; a users table allows you to write queries that include or exclude certain groups
2. Applications need to filter records using access controls that are consistent with file system permissions

Arrays provide a very natural means of associating group membership in a database. Since arrays are ordered, we can assign special meaning to the first member

CREATE TABLE users (
  username varchar(32) PRIMARY KEY,
  unix_groups varchar(32)[]  -- first element is the primary group
);

I may be mistaken, but I believe the ability to replicate a subset of data between databases that are otherwise unrelated has become a unique feature of relational databases. Unlike statement-based replication, logical replication is PostgreSQL is based on the WAL, and enables strict guarantees. It's also a modular architecture, but the built-in plugin (pgoutput) can usually be assumed.

The PostgreSQL server does not have a feature called "autocomit", but the most popular database library for Python, psycopg2 has it enabled by default. I say "enabled", but to disable this behavior we have to turn something on

conn.autocommit = True

The psycopg2 documentation has a warning about the default behavior

Warning: By default, any query execution, including a simple SELECT will start a transaction

Haml combines a set of valuable features:

1. A notation that mirrors HTML
2. Inline scripting and control flow
3. Blocks of text can be interpreted using custom filters

Haml 6+ introduced many breaking changes in the library and command line. Critically, there is no means of passing arguments or locals to the haml render command. To work around this use gem install -v 5.2.2.

• Boot parameters set on boot (example: switch to serial port)
• Configuration of network interfaces
• Partitioning & adaptive disklabels
• Selection and installation of base sets
• Custom site package that can contain arbitrary content
• Installation of non-root user with SSH public key
• Applying patches on first boot