github.com/hugorut/terraform@v1.1.3/website/docs/language/functions/substr.mdx (about)

     1  ---
     2  page_title: substr - Functions - Configuration Language
     3  description: |-
     4    The substr function extracts a substring from a given string by offset and
     5    length.
     6  ---
     7  
     8  # `substr` Function
     9  
    10  `substr` extracts a substring from a given string by offset and length.
    11  
    12  ```hcl
    13  substr(string, offset, length)
    14  ```
    15  
    16  ## Examples
    17  
    18  ```
    19  > substr("hello world", 1, 4)
    20  ello
    21  ```
    22  
    23  The offset and length are both counted in _unicode characters_ rather than
    24  bytes:
    25  
    26  ```
    27  > substr("🤔🤷", 0, 1)
    28  🤔
    29  ```
    30  
    31  The offset index may be negative, in which case it is relative to the end of
    32  the given string.  The length may be -1, in which case the remainder of the
    33  string after the given offset will be returned.
    34  
    35  ```
    36  > substr("hello world", -5, -1)
    37  world
    38  ```