{"title":"Tau's TILs","link":[{"@attributes":{"href":"https:\/\/tau.garden\/til\/atom.xml","rel":"self","type":"application\/atom+xml"}},{"@attributes":{"href":"https:\/\/tau.garden\/til\/"}}],"generator":"Zola","updated":"2025-12-08T00:00:00+00:00","id":"https:\/\/tau.garden\/til\/atom.xml","entry":[{"title":"Reset authors for multiple Git commits","published":"2025-12-08T00:00:00+00:00","updated":"2025-12-08T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/git-rebase-reset-author\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/git-rebase-reset-author\/","content":"

From Jeff Kreeftmeijer<\/a>'s blog:<\/p>\n

\n

If for some reason (like breaking your configuration) you need to reset the author for a number of git commits, rebase with git-rebase --exec<\/code> and amend each commit<\/a>:<\/p>\n

git<\/span><\/span> rebase main --<\/span>exec<\/span> '<\/span>git commit --amend --reset-author --no-edit'<\/span><\/span><\/span>\n<\/span><\/code><\/pre>\n<\/blockquote>\n"},{"title":"spellout converts numbers to number words","published":"2025-12-08T00:00:00+00:00","updated":"2025-12-08T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/spellout\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/spellout\/","content":"
spellout<\/code> is a handy utility that converts numbers to words:<\/p>\n
$<\/span><\/span> spellout $<\/span>(<\/span>seq<\/span><\/span> 1 10<\/span>)<\/span><\/span><\/span>\n<\/span>one<\/span><\/span>\n<\/span>two<\/span><\/span>\n<\/span>three<\/span><\/span>\n<\/span>four<\/span><\/span>\n<\/span>five<\/span><\/span>\n<\/span>six<\/span><\/span>\n<\/span>seven<\/span><\/span>\n<\/span>eight<\/span><\/span>\n<\/span>nine<\/span><\/span>\n<\/span>ten<\/span><\/span>\n<\/span><\/code><\/pre>\n"},{"title":"Template Strings in Python","published":"2025-12-08T00:00:00+00:00","updated":"2025-12-08T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/template-strings\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/template-strings\/","content":"
from<\/span><\/span> string<\/span>.<\/span>templatelib<\/span><\/span> import<\/span><\/span><\/span><\/span><\/span> Interpolation<\/span><\/span>\n<\/span>\n<\/span>def<\/span><\/span> quote<\/span><\/span><\/span>(<\/span><\/span>input<\/span><\/span>:<\/span> str<\/span><\/span> |<\/span> Interpolation<\/span><\/span><\/span>)<\/span><\/span> <\/span>-><\/span> str<\/span><\/span><\/span>:<\/span><\/span>\n<\/span>    if<\/span> isinstance<\/span><\/span><\/span><\/span>(<\/span>input<\/span><\/span>,<\/span> Interpolation<\/span><\/span>)<\/span><\/span>:<\/span><\/span>\n<\/span>        return<\/span> f<\/span>"<\/span><\/span><\/span>\u00ab<\/span>{<\/span>input<\/span>.<\/span>value<\/span><\/span><\/span><\/span>}<\/span><\/span>\u00bb"<\/span><\/span><\/span>\n<\/span>    else<\/span>:<\/span><\/span>\n<\/span>        return<\/span> input<\/span><\/span>\n<\/span>\n<\/span>cheese<\/span><\/span> =<\/span> '<\/span><\/span><\/span>Camembert'<\/span><\/span><\/span>\n<\/span>cheese_2<\/span><\/span> =<\/span> '<\/span><\/span><\/span>Brie'<\/span><\/span><\/span>\n<\/span>template<\/span><\/span> =<\/span> t<\/span><\/span>'<\/span><\/span><\/span>Ah! We do have {<\/span>cheese}<\/span><\/span>, but no {<\/span>cheese_2}<\/span><\/span>.'<\/span><\/span><\/span>\n<\/span>rendered<\/span><\/span> =<\/span> '<\/span><\/span><\/span>'<\/span><\/span><\/span>.<\/span><\/span>join<\/span><\/span><\/span><\/span>(<\/span>quote<\/span><\/span><\/span><\/span>(<\/span>v<\/span><\/span>)<\/span><\/span> for<\/span> v<\/span> in<\/span><\/span> template<\/span><\/span>)<\/span><\/span>\n<\/span>#<\/span> >>> rendered\n<\/span><\/span>#<\/span> 'Ah! We do have \u00abCamembert\u00bb, but no \u00abBrie\u00bb.'\n<\/span><\/span><\/code><\/pre>\n"},{"title":"
: The Heading Group element","published":"2025-06-01T00:00:00+00:00","updated":"2025-06-01T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/hgroup\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/hgroup\/","content":"
The <hgroup><\/code> element allows grouping\na heading with another heading or a paragraph.<\/p>\n
This is really useful for subtitles or taglines:<\/p>\n
<<\/span><\/span>hgroup<\/span>><\/span><\/span>\n<\/span>    <<\/span>h1<\/span>><\/span><\/span>&<\/span>lt;<\/span><\/span>hgroup&<\/span>gt;<\/span><\/span><\/<\/span>h1<\/span>><\/span><\/span>\n<\/span>    <<\/span>p<\/span>><\/span><\/span>The Heading Group Element<\/<\/span>p<\/span>><\/span><\/span>\n<\/span><\/<\/span><\/span>hgroup<\/span>><\/span><\/span>\n<\/span><\/code><\/pre>\n"},{"title":"Creative Commons Symbols in Unicode","published":"2024-05-21T00:00:00+00:00","updated":"2024-05-21T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/cc-symbols\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/cc-symbols\/","content":"
\ud83c\udd0d \ud83c\udd0e \ud83c\udd0f \ud83c\udd6d \ud83c\udd6e \ud83c\udd6f<\/span><\/p>\n
(chart<\/a>)<\/p>\n"},{"title":"Disable User in GNOME Login Screen","published":"2023-12-21T00:00:00+00:00","updated":"2023-12-21T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/disable-user\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/disable-user\/","content":"
After digging around in AccountManager<\/a>'s source code for a bit\nI figured that the easiest way to hide\/disable a user in the login screen\nis to change the shell to \/sbin\/nologin<\/code>:<\/p>\n
sudo<\/span><\/span> chsh -<\/span>s<\/span> \/sbin\/nologin USERNAME<\/span>\n<\/span><\/code><\/pre>\n"},{"title":"Chunking A Large File","published":"2023-12-12T00:00:00+00:00","updated":"2023-12-12T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/split-cat\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/split-cat\/","content":"
Today I had the misfortune of having to transfer a file larger than 4\u202fGiB using a FAT32-formatted USB drive.<\/p>\n
The following command splits the file into chunks that are each at most 4 GiB large:<\/p>\n
split<\/span><\/span> --<\/span>bytes<\/span> 4G large_file<\/span>\n<\/span><\/code><\/pre>\n
The chunks are named xaa<\/code>, xab<\/code>, xac<\/code>, \u2026<\/p>\n
cat<\/span><\/span> x*<\/span> ><\/span> large_file<\/span>\n<\/span><\/code><\/pre>\n"},{"title":"Python's int(x) Rounds Towards Zero","published":"2023-09-23T00:00:00+00:00","updated":"2023-09-23T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/python-int-rounding\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/python-int-rounding\/","content":"
\n
[\u2026] For floating point numbers, this truncates towards zero.<\/p>\n<\/blockquote>\n
\n    \n    
Example<\/figcaption>\n    \n    
from<\/span><\/span> math<\/span><\/span> import<\/span><\/span><\/span><\/span><\/span> floor<\/span>,<\/span> ceil<\/span><\/span>\n<\/span>\n<\/span>assert<\/span>(<\/span>int<\/span><\/span><\/span><\/span>(<\/span>-<\/span>0.<\/span>8<\/span>)<\/span><\/span> ==<\/span> 0<\/span>)<\/span><\/span>\n<\/span>assert<\/span>(<\/span>floor<\/span><\/span><\/span><\/span>(<\/span>-<\/span>0.<\/span>8<\/span>)<\/span><\/span> ==<\/span> -<\/span>1<\/span>)<\/span><\/span>\n<\/span>assert<\/span>(<\/span>ceil<\/span><\/span><\/span><\/span>(<\/span>-<\/span>0.<\/span>8<\/span>)<\/span><\/span> ==<\/span> 0<\/span>)<\/span><\/span>\n<\/span><\/code><\/pre>\n\n<\/figure>\n
Fleurons<\/a> are a decorative typographical element that usually take the form\nof flowers or leaves.\nA use that I recently became fond of is the use of a fleuron<\/a> as dinkus<\/a> to symbolize a logical break:<\/p>\n
\n
Wiki Commons has a handy list<\/a> of fleurons in SVG format.<\/p>\n"},{"title":"SQLite rowid as Foreign Key","published":"2023-09-10T00:00:00+00:00","updated":"2023-09-10T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/sqlite-rowid-fk\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/sqlite-rowid-fk\/","content":"
I was really excited when I first learned<\/a> about SQLite's rowid<\/code> feature.<\/p>\n
There is however a downside to the automatic rowid<\/code> column: It can't be used as part of foreign keys.\nQuoting from the SQLite docs<\/a> (emphasis is mine):<\/p>\n
\n
[\u2026]. The parent key must be a named column or columns in the parent table, not the rowid.<\/strong><\/p>\n<\/blockquote>\n
Fixing this downside is easy: Just add an INTEGER PRIMARY KEY<\/code> column\u2014it will get aliased to the rowid<\/code> column\n(See \u00abROWIDs and the INTEGER PRIMARY KEY\u00bb<\/a>):<\/p>\n
CREATE<\/span> TABLE<\/span> <\/span>example<\/span><\/span>\n<\/span>    ( id INTEGER<\/span> PRIMARY KEY<\/span>\n<\/span>    , ...\n<\/span>    );\n<\/span><\/code><\/pre>\n"},{"title":"Launching Sublime Merge via CLI","published":"2023-06-03T00:00:00+00:00","updated":"2023-06-03T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/sublime-merge\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/sublime-merge\/","content":"
Apart from the primary use case of opening a path by using smerge <path><\/code>\nyou can also open other tools such as blame (smerge blame<\/code>) or log (smerge log<\/code>).<\/p>\n"},{"title":"\u00ac\u03c6 \u2194 \u03c6 \u2192 \u22a5","published":"2023-04-15T00:00:00+00:00","updated":"2023-04-15T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/logical-not\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/logical-not\/","content":"\n
\u03c6<\/th>\u00ac\u03c6<\/th>\u03c6 \u2192 \u22a5<\/th>\u00ac\u03c6 \u2194 (\u03c6 \u2192 \u22a5)<\/th><\/tr><\/thead>
\u22a4<\/td>\u22a5<\/td>\u22a5<\/td>\u22a4<\/td><\/tr>\n
\u22a5<\/td>\u22a4<\/td>\u22a4<\/td>\u22a4<\/td><\/tr>\n<\/tbody><\/table>\n"},{"title":"0\u2070","published":"2022-10-23T00:00:00+00:00","updated":"2022-10-23T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/0-pow-0\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/0-pow-0\/","content":"
I have always assumed that $0^0$ is undefined with the same \u00abseverity\u00bb as $0 \\div 0$,\nbut in a lot of contexts<\/a>, it is actually defined as $0^0 = 1$. 
\nMost notably to me in this category are the IEEE floating-point numbers 1<\/a><\/sup>.<\/p>\n
1<\/sup>\n
There is technically the powr<\/code> function, which treats $0^0$ as NaN<\/code>, but most programming languages use the pow<\/code> function.<\/p>\n<\/div>\n"},{"title":"Non-Constructive Proofs","published":"2022-10-23T00:00:00+00:00","updated":"2022-10-23T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/non-constructive-proofs\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/non-constructive-proofs\/","content":"
Non-constructive proofs are a neat trick to show the existence of something without providing an example.<\/p>\n
A common example<\/a> for such a proof is for the theorem \u00abthere exist two irrational numbers $a$ and $b$ such that $a^b$ is rational.\u00bb\nIt goes as follows:<\/p>\n
Let $a = b = \\sqrt{2}$<\/p>\n
$a^b = \\sqrt{2}^{\\sqrt{2}}$ is either rational or irrational<\/p>\n
    \n
  1. If it is rational then our statement is proved.<\/li>\n
  2. If it is irrational, then we can pick $a = \\sqrt{2}^{\\sqrt{2}}$. 
    \n$(\\sqrt{2}^{\\sqrt{2}})^{\\sqrt{2}} = \\sqrt{2}^2 = 2$, which is rational.<\/li>\n<\/ol>\n"},{"title":"Python doctest","published":"2022-10-23T00:00:00+00:00","updated":"2022-10-23T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/python-doctest\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/python-doctest\/","content":"
    I've recently picked up Python again, and a neat feature that I ran across by chance is\nthe doctest<\/code> module. 
    \nIt tests if the example in your docstrings actually do what you claim!     1<\/a><\/sup><\/p>\n
    Let's say we have this neat is_leap_year<\/code> function with a few examples. 
    \nNote that the examples are all prefixed with >>> <\/code> (That's from the interactive prompt.)<\/p>\n
    def<\/span><\/span> _is_leap_year<\/span><\/span><\/span>(<\/span><\/span>year<\/span><\/span>:<\/span> int<\/span><\/span><\/span>)<\/span><\/span> <\/span>-><\/span> bool<\/span><\/span><\/span>:<\/span><\/span>\n<\/span>    """<\/span>Determines if a year is a leap year.\n<\/span><\/span>    >>> _is_leap_year(2020)\n<\/span><\/span>    True\n<\/span><\/span>    >>> _is_leap_year(2100)\n<\/span><\/span>    False\n<\/span><\/span>    >>> _is_leap_year(2000)\n<\/span><\/span>    True\n<\/span><\/span>    """<\/span><\/span>\n<\/span>    return<\/span> divides<\/span><\/span><\/span><\/span>(<\/span>400<\/span>,<\/span> year<\/span><\/span>)<\/span><\/span> or<\/span> (<\/span>divides<\/span><\/span><\/span><\/span>(<\/span>4<\/span>,<\/span> year<\/span><\/span>)<\/span><\/span> and<\/span> not<\/span> divides<\/span><\/span><\/span><\/span>(<\/span>100<\/span>,<\/span> year<\/span><\/span>)<\/span><\/span>)<\/span><\/span>\n<\/span>\n<\/span>if<\/span> __name__<\/span><\/span> ==<\/span> '<\/span><\/span><\/span>__main__'<\/span><\/span><\/span>:<\/span><\/span>\n<\/span>    import<\/span> doctest<\/span><\/span><\/span>\n<\/span>    doctest<\/span><\/span>.<\/span><\/span>testmod<\/span><\/span><\/span><\/span>(<\/span>)<\/span><\/span>\n<\/span><\/code><\/pre>\n
    Calling doctest.testmod<\/code> looks at all the examples in this module, runs the code and compares the result.<\/p>\n
Sublime Merge<\/a> can be launched using the smerge<\/code> command\nsimilar to the subl<\/code> command for Sublime Text<\/a>.<\/p>\n
If you want the floored result, you need to use math.floor<\/code><\/a>.\nIf you want the ceilling result, you need to use math.ceil<\/code><\/a>.<\/p>\n"},{"title":"Fleurons","published":"2023-09-18T00:00:00+00:00","updated":"2023-09-18T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/tau.garden\/til\/fleurons\/","type":"text\/html"}},"id":"https:\/\/tau.garden\/til\/fleurons\/","content":"
I was surprised to learn that Python's int<\/code><\/a> function rounds floats towards zero. 
\nHere's the relevant excerpt from the official docs<\/a>:<\/p>\n
On the other side one can use cat<\/code><\/a> to reconstruct the file from its chunks:<\/p>\n
Luckily there's the handy split<\/code><\/a> command that splits a file into multiple chunks.<\/p>\n
There are dedicated Unicode symbols<\/a> for Creative Commons licenses such as\nCC0 \/ share alike \/ attribution, etc.<\/p>\n
Python has template strings<\/a> that allow you to process the\nstrings and interpolations before creating the final string:<\/p>\n