substr

substr <string> <start> <len>

Extract a substring of up to len characters, starting at a 0-based offset.

Arguments

<string> — the source text.
<start> — an int, the 0-based index of the first character to copy. A negative start is treated as 0. A start at or past the end of the string yields the empty string.
<len> — an int, the maximum number of characters to copy. The result is clamped to the end of the string, so it may be shorter than len. A negative len is treated as 0.

A string — the copied characters. The source is never modified.

after command (say) {
  do "say [substr "hello world" 0 5]"
}

This copies five characters from offset 0, so the mob says hello.

after command (say) {
  do "say [substr "hello world" 6 100]"
}

The length runs past the end of the string, so it clamps: the mob says world (everything from offset 6 onward).