islink

by Tim C. Lueth, SG-Lib Toolbox: SolidGeometry 5.6 - File handling
Introduced first in SolidGeometry 5.1, Creation date: 2021-03-19, Last change: 2025-09-15

returns wether a file is just a link

Description

implemented at the moment only for mac osx 10.15.7.
This function is important to avoid copying a link over the original document when using copyfile or movefile and thus losing the content. Links/aliases should not be copied

See Also:

Example Illustration

missing image of islink(fname)

Syntax

islink=islink(fname)

Input Parameter

fname: file name

Output Parameter

islink: yes if the fname is a link

Examples


islink('/Users/lueth/Desktop/LUETH-WIN Alias')



Copyright 2021-2025 Tim C. Lueth. All rights reserved. The code is the property of Tim C. Lueth and may not be redistributed or modified without explicit written permission. This software may be used free of charge for academic research and teaching purposes only. Commercial use, redistribution, modification, or reverse engineering is strictly prohibited. Access to source code is restricted and granted only under specific agreements. For licensing inquiries or commercial use, please contact: Tim C. Lueth

Algorithm (Workflow)

This function, islink, determines if a given file is a link (alias) on macOS 10.15.7. It is part of the SolidGeometry library and is specifically designed to prevent copying links instead of the original files.

Input Parameters

Output Results

Algorithm Steps

  1. Check if the operating system is macOS using ismac. If not, display a warning that the function is not tested on other systems.
  2. Define a byte sequence maclnk that represents the header of a macOS alias file.
  3. Check if the file specified by fname exists using isfile.
  4. If the file exists, open it in read mode using fopen. If the file cannot be opened, display an error message.
  5. Read the first few bytes of the file using fgets to match the length of maclnk.
  6. Compare the read bytes with maclnk using isequal. If they match, set islink to true, indicating the file is a link.
  7. If the file does not exist, set islink to false.
  8. If no output argument is specified, print the read bytes using dbprintf.
Algorithm explaination created using ChatGPT on 2025-08-19 01:01. (Please note: No guarantee for the correctness of this explanation)

Last html export of this page out of FM database by TL: 2025-09-21