Replace A Range Of Lines (LCC.web_file.set_range_lines)

Signature

ok, replaced_or_err = LCC.web_file.set_range_lines(path, start_line, lines, timeout?)

Parameters

• path
  String. File path.
• start_line
  Number. Starting line index; positive numbers start at 1, negative values count from the end (-1 is the last line), and 0 means after the end.
• lines
  Table. Array of new line strings.
• timeout
  Number, optional. Request timeout in seconds, default 60.

Returns

• ok
  Boolean. true on success, false on failure.
• replaced_or_err
  Table or string. Replaced original lines on success, or the error description on failure.

Notes

Overwrites multiple lines at once starting from the given position.
Each empty string in the array represents a blank line, including at the end; for example, {"New content", ""} replaces two lines.
An empty array {} contains no replacement lines and differs from an array containing one empty string, {""}.
See the parameter description above for line-number rules.
When the target position is beyond the current end, blank lines are padded automatically.
Returns {} when no existing lines were replaced.
The returned old content is useful for auditing or undo flows.

Pairing reads and writes

When a file ends with a newline, get_lines keeps the empty string produced by splitting at the end. For example, the two-line text "A\nB\n" returns {"A", "B", ""}; passing this array to set_range_lines(path, 1, lines) writes three lines, with a blank last line.

To read and replace content by line number, pair get_range_lines with set_range_lines. To read, modify, and overwrite the whole file, pair get_lines with set_lines. set_lines overwrites the entire file and is not suitable for partial replacements.

In both pairs, reading and writing are separate requests, so the complete read-modify-write sequence is not atomic. Coordinate access when there are concurrent writes to avoid overwriting changes made after the read.

Example

local ok, old_lines_or_err = LCC.web_file.set_range_lines("/config/list.txt", 2, {"Beta", "Gamma"})
if ok then
    print("Original:", table.concat(old_lines_or_err, ","))
end