Rename a file

In this task, the job is to rename the file called "input.txt" into "output.txt" and a directory called "docs" into "mydocs". This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root.

Bash

 mv input.txt output.txt
 mv /input.txt /output.txt
 mv docs mydocs
 mv /docs /mydocs

DOS

 ren input.txt output.txt
 ren \input.txt \output.txt

Java

import java.util.File;
public class FileRenameTest {
   public static boolean renameFile(String oldname, String newname) {
       // File (or directory) with old name
       File file = new File(oldname);
   
       // File (or directory) with new name
       File file2 = new File(newname);
   
       // Rename file (or directory)
       boolean success = file.renameTo(file2);
       return sucess;
   }
   public static void test(String type, String oldname, String newname) {
       System.out.println("The following " + type + " called " + oldname +
           ( renameFile(oldname, newname) ? " was renamed as " : " could not be renamed into ")
           + newname + "."
       );
   }
   public static void main(String args[]) {
        test("file", "input.txt", "output.txt");
        test("file", File.seperator + "input.txt", File.seperator + "output.txt");
        test("directory", "docs", "mydocs");
        test("directory", File.seperator + "docs" + File.seperator, File.seperator + "mydocs" + File.seperator);
   }
}

Perl

   sub renameFile($$) {
       my ($oldname, $newname) = @_;
       return rename($oldname, $newname);
   }
   sub test($$$) {
       my ($type, $oldname, $newname) = @_;
       print "The following " . $type . " called " . $oldname, .
           ( renameFile($oldname, $newname) ? " was renamed as " : " could not be renamed into ")
           . $newname . ".";
   }
   my $FileSeperator = ($^O eq "MSWin32") ? "\\" : "/";
   test("file", "input.txt", "output.txt");
   test("file", $FileSeperator . "input.txt", $FileSeperator . "output.txt");
   test("directory", "docs", "mydocs");
   test("directory", $FileSeperator + "docs" . $FileSeperator, $FileSeperator + "mydocs" + $FileSeperator);
   exit;

# Short version
my $FileSeperator = ($^O eq "MSWin32") ? "\\" : "/";
rename("input.txt", "output.txt");
rename($FileSeperator . "input.txt", $FileSeperator . "output.txt");
rename("docs", "mydocs");    
rename($FileSeperator + "docs" . $FileSeperator, $FileSeperator + "mydocs" + $FileSeperator);

Tcl

Assuming that the Bash example shows what is actually meant with this task (one file and one directory here, one file and one directory in the root) and further assuming that this is supposed to be generic (i.e. OS agnostic):

 file rename inputs.txt output.txt
 file rename docs mydocs

 file rename [file nativename /inputs.txt] [file nativename /output.txt]
 file rename [file nativename /docs] [file nativename /mydocs]