document createSymbolicLink

Author: scivision

+stdlib/create_symlink.m

@@ -29,6 +29,8 @@
     % https://www.mathworks.com/help/releases/R2024b/matlab/ref/createsymboliclink.html
     % ok = java.nio.file.Files.createSymbolicLink(java.io.File(link).toPath(), java.io.File(target).toPath());
     % Matlab Java doesn't recognize the optional argument omitted.
+    % see example/Filesystem.java for this working in plain Java.
+    % see example/javaCreateSymbolicLink.m for a non-working attempt in Matlab.
 
     if ispc
       cmd = "pwsh -c " + '"' + "New-Item -ItemType SymbolicLink -Path " + link + ...

example/Filesystem.java

@@ -9,49 +9,54 @@
 
 import java.util.Scanner;
 import java.io.File;
+import java.nio.file.Path;
 
 
 public class Filesystem {
-    public static void main(String[] args) {
+    public static void main(String[] argv) {
         Scanner scanner = new Scanner(System.in);
 
-        String argument = "";
+        String a1 = "";
+        String a2 = "";
         final String prompt = "Jfs> ";
 
         System.out.print(prompt);
 
         while (scanner.hasNextLine()) {
             String input = scanner.nextLine();
 
-            String[] inputArray = input.split(" ");
-            String command = inputArray[0];
+            String[] args = input.split(" ");
+            String command = args[0];
 
-            if (inputArray.length > 1) {
-                argument = inputArray[1];
-            } else {
-                argument = "";
+            if (args.length > 1) {
+                a1 = args[1];
+            }
+            if (args.length > 2) {
+                a2 = args[2];
             }
 
             if (command.equals("exit") || command.equals("q") || command.equals("\u0004")) {
                 break;
             } else if (command.equals("java_version")) {
                 System.out.println(System.getProperty("java.version"));
             } else if (command.equals("absolute")) {
-                System.out.println(absolute(argument));
+                System.out.println(absolute(a1));
+            } else if (command.equals("create_symlink")) {
+                System.out.println(create_symlink(a1, a2));
             } else if (command.equals("expanduser")) {
-                System.out.println(expanduser(argument));
+                System.out.println(expanduser(a1));
             } else if (command.equals("canonical")) {
-                System.out.println(canonical(argument));
+                System.out.println(canonical(a1));
             } else if (command.equals("parent")) {
-                System.out.println(parent(argument));
+                System.out.println(parent(a1));
             } else if (command.equals("root")) {
-                System.out.println(root(argument));
+                System.out.println(root(a1));
             } else if (command.equals("is_absolute")) {
-                System.out.println(is_absolute(argument));
+                System.out.println(is_absolute(a1));
             } else if (command.equals("is_exe")) {
-                System.out.println(is_exe(argument));
+                System.out.println(is_exe(a1));
             } else if (command.equals("is_readable")) {
-                System.out.println(is_readable(argument));
+                System.out.println(is_readable(a1));
             } else if (command.equals("ram_free")) {
                 System.out.println(ram_free());
             } else if (command.equals("cpu_count")) {
@@ -71,6 +76,18 @@ public static String absolute(String path) {
         return f.getAbsolutePath();
     }
 
+    public static Boolean create_symlink(String target, String link) {
+        Path t = new File(target).toPath();
+        Path l = new File(link).toPath();
+        try {
+            java.nio.file.Files.createSymbolicLink(l, t);
+            return true;
+        } catch (java.io.IOException e) {
+            System.err.println(e);
+            return false;
+        }
+    }
+
     public static String expanduser(String path) {
         if (path.startsWith("~"))
             return System.getProperty("user.home") + path.substring(1);

example/javaCreateSymbolicLink.m

@@ -0,0 +1,14 @@
+f = stdlib.absolute("Readme.md");
+link = "alsoread.md";
+
+perms = stdlib.get_permissions(f);
+
+pp = java.nio.file.attribute.PosixFilePermissions.fromString(perms);
+
+fp = java.nio.file.attribute.PosixFilePermissions.asFileAttribute(pp);
+
+tp = java.io.File(f).toPath();
+lp = java.io.File(link).toPath();
+
+java.nio.file.Files.createSymbolicLink(lp, tp, fp);
+% this fails with No method 'java.nio.file.Files.createSymbolicLink' with matching signature found.