Merge commit 'b9bd35d72e14932fb6588ff62b90cddef0a060fc' as 'docs'

docs/content/en/functions/substr.md

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+---
+title: substr
+# linktitle:
+description: Extracts parts of a string from a specified character's position and returns the specified number of characters.
+godocref:
+date: 2017-02-01
+publishdate: 2017-02-01
+lastmod: 2017-02-01
+categories: [functions]
+menu:
+  docs:
+    parent: "functions"
+keywords: [strings]
+aliases: []
+signature: ["substr STRING START [LENGTH]"]
+workson: []
+hugoversion:
+relatedfuncs: []
+deprecated: false
+---
+
+It normally takes two parameters: `start` and `length`. It can also take one parameter: `start`, i.e. `length` is omitted, in which case the substring starting from start until the end of the string will be returned.
+
+To extract characters from the end of the string, use a negative start number.
+
+In addition, borrowing from the extended behavior described at https://php.net substr, if `length` is given and is negative, that number of characters will be omitted from the end of string.
+
+```
+{{substr "BatMan" 0 -3}} → "Bat"
+{{substr "BatMan" 3 3}} → "Man"
+```