35 lines
1.3 KiB
Markdown
35 lines
1.3 KiB
Markdown
# extremely brief regex overview
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Regexes are powerful. Gitolite uses that power as much as it can. If you
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can't handle that power, hire someone who can and become a manager.
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That said, here's a very quick overview of the highlights.
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`^` and `$` are called "anchors". They anchor the match to the beginning and
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end of the string respectively.
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^foo matches any string starting with 'foo'
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foo$ matches any string ending with 'foo'
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^foo$ matches exact string 'foo'.
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To be precise, the last one is "any string starting and ending with *the same*
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'foo'". "foofoo" does not match.
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`[0-9]` is an example of a character class; it matches any single digit.
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`[a-z]` matches any lower case alpha, and `[0-9a-f]` is the range of hex
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characters. You should now guess what `[a-zA-Z0-9_]` does.
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`.` (the period) is special -- it matches any character. If you want to match
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an actual period, you need to say `\.`.
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`*`, `?`, and `+` are quantifiers. They apply to the previous token. `a*`
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means "zero or more 'a' characters". Similarly `a+` means "one or more", and
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`a?` means "zero or one".
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As a result, `.*` means "any number (including zero) of any character".
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The previous token need not be a single character; you can use parens to make
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it longer. `(foo)+` matches one or more "foo", (like "foo", "foofoo",
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"foofoofoo", etc.)
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