about PATH_MAX: the part of the POSIX standard which determines the maximum number of bytes allowed in an absolute path. In Linux, PATH_MAX is 4096 [src], but it’s possible to construct longer paths if you don’t care about some (most) utilities that use the current working directory to fail due to buffer overflow.
Also, I learned that most filesystems restrict file names to 255 bytes.
That the IANA suggests 49152–65535 (215 + 214 to 216 − 1) for dynamic or private ports. source: https://en.wikipedia.org/wiki/Ephemeral_port#Range
locate searches all filenames for a keyword using a database which you can update updatedb.
whereis searches for binaries using the same mechanism.
https://www.madebygps.com/an-intro-to-finding-things-in-linux/
that sudo can be configured with the visudo command and that sudo can produce audit logs.
See https://www.sudo.ws/posts/2022/05/sudo-for-blue-teams-how-to-control-and-log-better/
that there’s an Element.closest(selector) method, which means you can run this function to set the url to the closest link to an element:
((el) => {
let id = el.closest("[id]")?.id;
if (!id) return;
else location.hash = id;
})($0);
that you can use
SELECT /*...*/
FROM one_table
JOIN other_table
USING (common_column)
as shorthand for one_table.common_column = other_table.common_column.
See https://www.postgresql.org/docs/current/sql-select.html#SQL-FROM
That linux has a capability system: https://man7.org/linux/man-pages/man7/capabilities.7.html
I heard about this in a discussion of privileged ports on linux, specifically about PRIV_NET_PRIVADDR.
That there’s a Linux command to do sql-like JOINs of lines in files, possibly based on a field in each line: join(1)
That the GPU I have in the Ubuntu workstation in my office isn’t compatible with ROCm, AMD’s GPU compatibility layer, or Vulkan. I was trying to run the binary for tabby locally. First, I looked up my graphics card:
; lshw -c video
# *-display
# description: VGA compatible controller
# product: Turks PRO [Radeon HD 7570]
# vendor: Advanced Micro Devices, Inc. [AMD/ATI]
# physical id: ...
# bus info: pci@0000:01:00.0
# logical name: /dev/fb0
# version: 00
# width: 64 bits
# clock: 33MHz
# capabilities: vga_controller bus_master cap_list rom fb
# configuration: depth=32 driver=radeon latency=0 resolution=2048,1080
# resources: irq:42 memory:e0000000-efffffff memory:f0020000-f003ffff ioport:e000(size=256) memory:c0000-dffff
I followed a few false starts, during which I learned:
These are obvious in hindsight, but here are some of the commands I learned figuring out how I shot myself in the foot:
grep 'GRUB_CMDLINE_LINUX' /etc/default/grub
sudo vi /etc/default/grub # edit kernel flags
cat /proc/cmdline # display kernel flags in **current** session
update-grub # actually apply edited settings
inxi -G # display graphics hardware
sudo apt install inxi
sudo apt install vulkan-tools
vulkaninfo # display vulkan config.
I finally found the smoking gun in a 2020 wiki post on old GPUs. Turns out the 7570 came out in 2012 – while Vulkan was only standardized in 2016.
This is a bummer, but there’s a nonzero chance one of my other salvaged boxes have newer chips.