Develop Reference

How to delete all files in directory but keep the file that a symbolic link is pointing to?

This has been identified as a possible duplicate of another question on here, it is not. I know how to delete the symbolic link and the files. I am trying to keep the file associated with the symbolic link but delete everything else.
My Problem: Delete all files in directory older than 7 days except files associated with symbolic link.
Issue: Symbolic link successfully deleted but remaining older files are not removed.
Details: I am trying to write a simple Java program to delete all of the files and subfolders in a directory older than 7 days which is working but there is one issue. If there is a symbolic link then I need to delete just the link and keep the file that it links to. Other than that case, everything else gets deleted. I know that I am very close... if you have any suggestions let me know please. At the moment I am able to have it delete the symbolic link but the other old files are not being deleted when they should. This could be a simple logic error or maybe I am approaching the problem the wrong way. Thanks in advance!
import java.nio.file.Files;
import java.nio.file.Paths;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
public class delcache {
public static void main(String[] args) throws IOException
{
String path1="/home/test/cachetest";
recursiveDelete(7, path1);
}
public static void recursiveDelete(int days, String dirPath) throws IOException {
long cutOff = System.currentTimeMillis() - (days * 24 * 60 * 60 * 1000);
Files.list(Paths.get(dirPath))
.forEach(path -> {
if (Files.isDirectory(path)) {
try {
recursiveDelete(days, path.toString());
} catch (IOException e) {
// log
}
} else {
try {
if (Files.getLastModifiedTime(path).to(TimeUnit.MILLISECONDS) < cutOff) {
String pathsave = null;
if(Files.isSymbolicLink(path)) {
pathsave = path.toRealPath().toString();
System.out.println("pathsave: " + pathsave);
System.out.println("delete symlink: " + path);
Files.delete(path);
}
if(!(Files.isSymbolicLink(path))) {
System.out.println("pathsave: " + pathsave);
if(!(path.toString().equals(pathsave))) {
System.out.println("not equal so delete file: " + path);
Files.delete(path);
}
}
//Files.delete(path);
}
} catch (IOException ex) {
// log
}
}
});
}
}

Your logic is flawed, String pathsave persists only for the current loop of the specific path. when the loop gets to actual file the pathsave is always null.
if you want to save the symbolic links path you need to have a list of paths which is outside the function. even then it won't work because you have no guarantee for any order, you may first reach to the symbolic link or first reach the file.
So as I understand it you must first iterate the folder looking for all the symbolic links, save them into global List which is accessible to the method, and then run and delete the files.
side note: notice that if you delete the symboic links, the next time you would run this function, the same files which previously had symlinks will now be deleted
public static void main(String[] args) throws IOException
{
String path1="/home/test/cachetest";
List<Path> symlinks = getAllSymLinks(path1);
recursiveDelete(7, path1, symlinks);
}
public static List<Path> getAllSymLinks(String dirPath) throws IOException {
List<Path> paths = new ArrayList<>();
Files.list(Paths.get(dirPath))
.forEach(path -> {
if (Files.isDirectory(path)) {
try {
paths.addAll(recursiveDelete(days, path.toString()));
} catch (IOException e) {
// log
}
} else {
try {
if(Files.isSymbolicLink(path)) {
paths.add(path.toRealPath());
}
} catch (IOException ex) {
// log
}
}
});
return paths;
}
public static void recursiveDelete(int days, String dirPath, List<path> symlinks) throws IOException {
long cutOff = System.currentTimeMillis() - (days * 24 * 60 * 60 * 1000);
Files.list(Paths.get(dirPath))
.forEach(path -> {
if (Files.isDirectory(path)) {
try {
recursiveDelete(days, path.toString(), symlinks);
} catch (IOException e) {
// log
}
}
else {
try {
if (Files.getLastModifiedTime(path).to(TimeUnit.MILLISECONDS) < cutOff &&
!Files.isSymbolicLink(path) &&
!symlinks.contains(path))
{
Files.delete(path);
}
} catch (IOException ex) {
// log
}
}
});

You could use this method:
Use Process process = Runtime.getRuntime.exec("ls -l") to list all contents of the directory.
Read the InputStream of process line by line.
If the first character is 'd', the file in the line is a directory. Recurse.
If the first character is '-', delete.
If the first character is 'l', it is a symbolic link. Skip the file.
You can get the filename from the same line. For example, if the line is in a variable 'str', the the filename is str.split("\\s+")[8]
You can additionally use the filenames for any other checks you require.
EDIT
Untested method using grep:
String getLinkedFile(file) {
// Input: A Symbolic link file
// Output: Name of file pointed to by the symlink
Process p = Runtime.getRuntime.exec("ls -l | grep -e \"->\"");
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((line = reader.readLine()) != null) {
String []tokens = line.split("\\s+");
String linkFile = tokens[8];
if(linkFile.equals(file.getName()))
return tokens[10];
}
return null;
}
You may need to modify this function based on file paths.

Recursion method continues after returning value?

I'm writing a quick Java recursion method that, given a root folder and filename, searches your files for said file name.
import Java.io.File;
public static String searchForFile(File currentFolder, String filename)
{
try
{
File[] path = currentFolder.listFiles();
for (int i = 0; i < path.length; i++)
{
if (path[i].isDirectory())
{
System.out.println("Directory: " + path[i].toString());
searchForFile(path[i], filename);
}
else
{
System.out.println("File: " + path[i].toString());
if(path[i].getName().equals(filename))
{
System.out.println("Your file has been found!";
return path[i].toString();
}
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
return null; // Omitting this line yields compiling errors, not sure why?
}
public static void main(String[] args)
{
System.out.println("Hello, enter the root folder and file name.");
String rootFolder = "Desktop";
String fileName = "Hello.txt";
File f = new File("C:\\Users\\Me\\" + rootFolder);
searchForFile(f, fileName);
}
The program itself technically works, however searchForFile() keeps iterating even after the requested file is found. For example, I'd get an output such as:
File: C:\Users\Me\Desktop\My Stuff\NotHello.txt
**File: C:\Users\Me\Desktop\My Stuff\Hello.txt**
Your file has been found!
File: C:\Users\Me\Desktop\My Stuff\AlsoNotHello.txt
File: C:\Users\Me\Desktop\My Stuff\StillNotHello.txt
File: C:\Users\Me\Desktop\My Stuff\WhyIsThisMethodStillRunning.txt
I've been scratching my head at this for awhile now. I thought return always exits the method, so why does the recursion continue even after it returns a value? I haven't found any similar questions asked, so any help would be much appreciated!
(Also, how could I edit the method so that it returns a blank "" string if the requested file is not found?)

You are returning from the innermost call, when you've found the file. But when you are scanning a directory, you are not using the return value.
Change this:
searchForFile(path[i], filename);
to:
String result = searchForFile(path[i], filename);
if (result != null) {
return result;
}
The return null; in the bottom of your method is there because all methods needs to return a value. No matter if the file is found or not. If the file is not found within the current directory (or one of its subdirectories), you can return null; to indicate that it wasn't found.
Side suggestion: Use Optional in Java 8 instead of null.

Running multiple Batch files from different threads Java

I have n number of thread getting created at run time according to the input source files present in a folder. For every thread, I have one common class which has all the functions present that are used by every thread. Every thing is working perfectly except the part where batch files are run.
I have main class which is creating thread(which is working perfectly fine). Then I am creating batch files with relevant contents( which is also running perfectly). After that, only 1(can be anyone, no specific pattern) thread is able to execute the batch file and not the others.
Code:
String batch_content = "echo off \n "
+ "powershell.exe -file "
+ utility_path + "convertCSVSwiss.ps1 " + fpath + filename + " -executionpolicy Unrestricted \n ";
String batch_name = "batch_" + fname +"_"+sdf.format(cal.getTime())+ ".bat";
Utils.createBatchFile(batch_content, bat_file_path, batch_name);
Utils.RunBatch(bat_file_path, batch_name,csv_file_path,fname);
Utils.createBatchFile is working fine which create a batch file with the batch content. But Utils.RunBatch seems to having some problem. Here is the code for RunBatch:
public static void RunBatch(String filepath, String filename,String csv_file_path,String fname) throws Exception {
try {
System.out.println("Started Program");
new File(csv_file_path + "\\" + fname).mkdir();
String filePath1 = filepath + filename;
System.out.println("Batch file running is " + filePath1);
Process p = Runtime.getRuntime().exec(new String[] { "cmd.exe", "/c", filePath1 });
p.getOutputStream().close();
p.waitFor();
} catch (Exception e) {
e.printStackTrace();
}
}
My log file prints this:
Batch file running is C:\ER\ETL\bat files\batch_Sample_Data_10_40_16_12_40_37.bat
Batch file running is C:\ER\ETL\bat files\batch_ssd_10_40_16_12_40_37.bat
but it runs only the first one.
Any help would be appreciated.
P.S I am sorry if I missed any information that may be necessary to get this problem resolved. Please let me know and I can then edit my post.
EDIT:
Here is my code.
//main class to start new thread for every excel file present in the source directory
public class LoadData{
public static void main(String[] args) throws Exception{
try{
File folder = new File(fpath);
File[] listoffiles = folder.listFiles();
for (int i = 0; i < listoffiles.length; i++) {
if (listoffiles[i].isFile()) {
filename = listoffiles[i].getName();
c = filename.lastIndexOf(".");
absfilename = filename.substring(0, c);
System.out.println("File name with extension is "+filename);
System.out.println("File name is "+absfilename);
System.out.println("Starting thread for "+absfilename);
ConvertToCSV et = new ConvertToCSV();
et.fpath = fpath;
et.utility_path=utility_path;
et.filename=filename;
et.fname = absfilename;
et.bat_file_path =bat_file_path;
et.tpath =tpath;
et.csv_file_path=csv_file_path;
Thread t = new Thread(et);
t.start();
}
}
}
catch (Exception e) {
e.printStackTrace();
}
}
}
//class to create the batch file content
public class ConvertToCSV implements Runnable{
String fpath,utility_path,filename,fname,bat_file_path,tpath,csv_file_path;
try{
String batch_content = "echo off \n "
+ "powershell.exe -file "
+ path_to_powershell_script_to_convert_excel_into_csv + "convertCSVSwiss.ps1 " + path_and_name_to_the_excel_file " -executionpolicy Unrestricted \n ";
String batch_name = "batch_" + excel_file_name +"_"+sdf.format(cal.getTime())+ ".bat";
Utils.createBatchFile(batch_content, bat_file_path, batch_name);
Utils.RunBatch(bat_file_path, batch_name,csv_file_path,fname);
}
catch (Exception e) {
e.printStackTrace();
}
}
public class Utils{
//function to create the batch file
public static void createBatchFile(String batch_content, String path, String batch_name) throws IOException {
String p = path + batch_name;
File batfile = new File(p);
FileWriter fw = new FileWriter(batfile);
fw.write(batch_content);
fw.close();
}
//function to run the batch file
public static void RunBatch(String filepath, String filename,String csv_file_path,String fname) throws Exception {
try {
System.out.println("Started Program");
new File(csv_file_path + "\\" + fname).mkdir();
String filePath1 = filepath + filename;
System.out.println("Batch file running is " + filePath1);
Process p = Runtime.getRuntime().exec(new String[] { "cmd.exe", "/c", filePath1 });
p.getOutputStream().close();
p.waitFor();
} catch (Exception e) {
e.printStackTrace();
}
}
}
EDIT2: I have added the run for ConvertTO CSV. My code is doing say 10 things, and 9 of them are working fine except running two batch files with different names from the same folder
public class ConvertToCSV implements Runnable{
String fpath,utility_path,filename,fname,bat_file_path,tpath,csv_file_path,pg_db_url,pg_db,pg_db_uid,pg_db_pwd,plpgsql_path,Log_Path;
SimpleDateFormat sdf = new SimpleDateFormat("dd_mm_yy_hh_mm_ss");
Calendar cal = Calendar.getInstance();
#Override
public void run() {
try {
runConvertToCSV(fpath,utility_path,filename,fname,bat_file_path,tpath,csv_file_path,plpgsql_path);
} catch (Exception e) {
e.printStackTrace();
}
}
private void runConvertToCSV(String fpath,String utility_path,String filename,String fname,String bat_file,String tpath,String csv_file_path,String plpgsql_path) throws Exception{try{
String batch_content = "echo off \n "
+ "powershell.exe -file "
+ path_to_powershell_script_to_convert_excel_into_csv + "convertCSVSwiss.ps1 " + path_and_name_to_the_excel_file " -executionpolicy Unrestricted \n ";
String batch_name = "batch_" + excel_file_name +"_"+sdf.format(cal.getTime())+ ".bat";
Utils.createBatchFile(batch_content, bat_file_path, batch_name);
Utils.RunBatch(bat_file_path, batch_name,csv_file_path,fname);
}
catch (Exception e) {
e.printStackTrace();
}
}
EDIT3#:
My guess was that maybe because all the batch files are trying to access the same powershell script, that is why it is not working. But then i created ps script for every batch file. Also, added error stream to the stdout to check if there is any error and this is what i am getting:
Standard Error:
The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)
At C:\ER\ETL\ETL_SOURCE\convertCSVSwiss_Swiss_Sample_Data.ps1:24 char:2
+ $Worksheet.SaveAs($ExtractedFileName,6)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : OperationStopped: (:) [], COMException
+ FullyQualifiedErrorId : System.Runtime.InteropServices.COMException
there are number of same error at different line. NOTE: It is the same ps script for all the batch files, it runs only for one and not for others. and that one can be anyone(no pattern).
If i run the above batch file manually, then it succeeds.

Optimising Java Scanner to match regex in file faster

I am currently using this code to match a regex against a lot of files, however, this is fairly slow. Is there a way I can do the same thing, but faster?
public class Filter {
private String title;
private String regex;
private List<String> results = new LinkedList<String>();
...
}
I have a few Filters for different types of regexes, they range from matching emails to matching words like apikey, ... The code will be used to scan for vulnerabilities in decompiled classes and other text based files.
My code also only checks for 1 match in a file, I'd like to get all matches.
public void startScans() {
List<File> files = getAllFiles(getFolder()); //Gets a list of all text based files in a folder
for (int i = 0; i < files.size(); i++) {
for(Filter filter : getFilters()) {
try {
System.out.print("\rScanning file " + i + " out of " + files.size() + " using filter " + filter.getTitle() + "...");
scanFile(files.get(i), filter);
} catch (FileNotFoundException ignored) {}
}
}
}
private void scanFile(File f, Filter filter) throws FileNotFoundException {
Scanner scanner = new Scanner(f);
String result = scanner.findWithinHorizon(filter.getRegex(), 0);
if (result != null) {
filter.addResult(result);
}
scanner.close();
}

You can also use an external tool if you want a faster execution, that is, execute a command. e.g.
Windows: findstr /R [a-z]*xyz *
Linux: egrep -R "[a-z]*xyz" .
NOTE: You can run these commands from Java.

problem with deleting files

private static void deletefile(String file) {
int fileName = 500;
int z;
String[] File = new String[fileName];
for (z = 0; z < fileName; z++) {
File f1 = new File(
"C:\\Users\\user\\fypworkspace\\TextRenderer\\abc" + z
+ ".txt");
boolean success = f1.delete();
if (!success) {
System.out.println("Deletion failed.");
System.exit(0);
} else {
System.out.println("File deleted.");
}
}
}
public static void main(String[] args) throws IOException {
switch (args.length) {
case 0:
System.out.println("File has not mentioned.");
System.exit(0);
case 1:
deletefile(args[0]);
System.exit(0);
default:
System.out.println("Multiple files are not allow.");
System.exit(0);
hi, this is my code for attempting to delete a certain files in java. It prints out file has not mentioned.i was trying to delete a set of txt files in a certain folder. The program should continue with the next file once a file is missing. Can anyone point out my mistake ? thanks..

Apparently you did not pass any command line parameters to your program.
(Although even if you did, it is not used anywhere in deletefile() - your method attempts to delete a fixed set of files in a specific directory, and if any of these is missing or you don't have permissions to delete it, it exits with an error message.)

You have to specify the file name as command line argument when running your Java program.
java MyClass file_to_delete

You need to have some check or catch exception when you create a new file so it wont stop when the file is not found.