sabi notes Notes mostly about Linux and computer topics sabico computing http://www.sabi.co.uk/ Copyright 2021 Peter G. http://www.sabi.co.uk/ 2024-07-19T23:25:00Z Account and identity, PulseAudio, etc. 2020-03-19T19:30:00Z 2020-03-19T19:30:00Z http://www.sabi.co.uk/blog/210319 PulseAudio confuses user numbers and account names, making it harder to have multiple account names per user numbers, but there is a workaround. Booting with GRUB2 from EFI, some details 2020-08-10T22:30:00Z 2020-08-10T22:30:00Z http://www.sabi.co.uk/blog/200810 Booting from EFI using GRUB2 involves several steps, some of which, at least under Ubuntu, are not so obvious. Two factors, things you have, things you know 2020-11-07T14:10:00Z 2020-11-07T14:10:00Z http://www.sabi.co.uk/blog/201107 Two factor authentication can be done in different ways, as long as it is recognized that the usual description of factor types is somewhat misleading, in particular for biometrics. Multiple passwords per UNIX account 2020-11-08T12:00:00Z 2020-11-08T12:00:00Z http://www.sabi.co.uk/blog/201108 it is possible in the default UNIX/Linux to have multiple user names per user number, but not multiple passwords per user name, which prevents some useful configurations. Impressions of a Lenovo E495 laptop 2020-12-30T11:10:00Z 2020-12-30T11:10:00Z http://www.sabi.co.uk/blog/201230 The ThinkPad E495 is excellent value for money with good performance, great expandability, the only non-trivial issue being a battery with limited capacity. Short proper names for devices and media 2021-05-03T20:20:00Z 2021-05-03T20:20:01Z http://www.sabi.co.uk/blog/210503 With some simple configuration it is possible and desirable to give proper names to specific media and devices. Updated CSS styles for ATOM and RSS feeds 2021-05-23T13:30:00Z 2021-05-23T13:30:00Z http://www.sabi.co.uk/blog/210523 I have updated and improved my CSS styles to render directly in a web browser ATOM and RSS feed files. A really nice typeface 2021-06-12T16:50:00Z 2021-06-12T16:50:00Z http://www.sabi.co.uk/blog/210612 Over the years I have become a fan of the Ubuntu typeface, which is highly legible and compact, and I prefer it even to DejaVu. Identifiable or self-identified targets 2021-06-23T18:10:00Z 2021-06-23T18:10:00Z http://www.sabi.co.uk/blog/210623 By using conveniences like online ordering it is much easier to be targeted by hostile operations. Much slower battery capacity decrease 2021-07-02T14:10:00Z 2021-07-02T14:10:00Z http://www.sabi.co.uk/blog/210702 After 6 months the battery of a new laptop had already lost 14% of its capacity. Setting a maximum charge threshold has dramatically slowed that down. A couple details about authentication tokens 2021-07-04T21:50:00Z 2021-07-04T21:50:00Z http://www.sabi.co.uk/blog/210704 Usuall three distinct second authentication factors should be registered with account. Also they are effectively unique identifiers, so using one for multiple accounts will mark them as belonging to the same entity, which may or may not matter. NFS and filesystem instances with multiple roots 2021-08-04T22:30:00Z 2021-08-04T22:30:00Z http://www.sabi.co.uk/blog/210804 A debate among Linux kernel developers about NFS and filesystem instances with multiple roots has one side arguing that there should be only one root per filesystem instance, but this is both a misunderstanding of UNIX filesystem semantics and unnecessary. Trends in computing in the past 20 years 2022-01-07T20:40:00Z 2022-01-07T20:40:00Z http://www.sabi.co.uk/blog/220107 A summary of some major and minor trends in computing. Changing DPI in X-Windows, 2022 edition 2022-03-05T18:20:00Z 2022-03-05T18:20:00Z http://www.sabi.co.uk/blog/220305 A script to change DPI reported or rendered by X Windows or major GUI libraries. Standard ratio for storage 2022-07-10T11:40:00Z 2022-07-10T11:40:00Z http://www.sabi.co.uk/blog/220710 For general purpose storage size, IOPS and transfer rate should increase together in the same proportion. A very odd behaviour of 'find' 2023-01-17T18:40:00Z 2023-01-17T18:40:00Z http://www.sabi.co.uk/blog/230117 The find option -size has a very odd with rounding up, and can only test for less-than a given size in a special case. Mount-point scheme to minimize chances of stuck processes 2023-01-23T2250:00Z 2023-01-23T2250:00Z http://www.sabi.co.uk/blog/230123 Mount points should be in a separate subtree from the working directories of other processes which requires two levels of directory, and ideally also soft-links. Impressively low power consumption of AMD laptop with Linux 2023-04-30T1330:00Z 2023-04-30T1330:00Z http://www.sabi.co.uk/blog/230430 On a cheap laptop recent kernels achieve faily low power consumption. CUPS backends and drivers 2023-12-30T0910:00Z 2023-12-30T0910:00Z http://www.sabi.co.uk/blog/231230 The official EPSON driver for it is not quite right, also new versions of CUPS do not use drivers but only support IPP, so for USB printers one must use an IPP-to-USB filter. IOPS, IOPS-per-TB, IOPS-per-inode 2024-01-04T1730:00Z 2024-01-04T1730:00Z http://www.sabi.co.uk/blog/240104 IOPS-per-TB is a very important overall metric for storage systems, but absolute IOPS and IOPS-per-"object" separately also are interesting. 'wireplumber' and Bluetooth 2024-07-19T2220:00Z 2024-07-19T2220:00Z http://www.sabi.co.uk/blog/240719 PipeWire seems better than PulseAudio, but to simplify its configuration it has two daemons that dynamically discover and configure audio devices, of which 'wireplumber' is the most recent, and its default discory logic needs modifying when 'systemd-logind' is present but is not used.