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MacOS Big Sur (version 11.0) is the next major release of macOS, Apple Inc.' S operating system for Macintosh computers. It is the successor to macOS Catalina (version 10.15) and was announced at Apple’s Worldwide Developers Conference on June 22, 2020, with public beta release scheduled for July and general release projected for fall. It is named after the coastal region of Big Sur in the.

WOW, nice script! I've actually been looking for something like this. Question, can this script actually run in the background and execute another script if the contents of a folder have changed??? Or does anyone else know of an alternative that will execute scripts when a file or contents of a folder have been changed?

You mentioned that it should work on any linux, well I tested it on SuSE Linux 8.2 and it works as it should! Thanks again for the nice script, I can find many uses for it! Another files that's fun to watch is /var/log/messages in linux ofcourse

Thank's, this is one of those things you never quite get around to writing, but wonder how you got by without once you use it.
I hope someone picks up the baton and builds a Cocoa app with a drag-and-drop file well. Sounds like a very nice project to start learning Cocoa. Maybe I can find time this fall. Of course then it's not so nice and portable anymore.
--Thank You
---
Mark Moorcroft
ELORET Corp. - NASA/Ames RC
Sys. Admin.

Tripwire does pretty much the same thing as this Perl script does with the -md5 option, but with the option of customizing what checks are performed on each category of files. So, for example, you can simply check to make sure that your log files haven't been deleted and haven't had their ownership changed, but you can also check to make sure that system executables haven't had their contents replaced with Trojan code. It takes a lot of work to customize properly, but once you're done, you can be relatively sure that you'll catch any system modifications that are done.

Tripwire has been available for Mac OS X for a few months now.

I think Tripwire occupies a different ecological niche. It is explicitly concerned with security and is far more sophisticated, with concomitant complexity of use.

Of similar sophistication but in a slightly different niche is Radmind - it is usually used for maintaining multiple machines in a known state.

A bit lower on the complexity scale but still considerably more sophisticated than the 'watchfile' script is the bubblegum program. It is a compiled C program that is designed to run as a daemon.

The 'watchfile' script was intended mostly for impromptu troubleshooting sessions where the ease of modification of a script (as opposed to a compiled executable) is often a big advantage.

hayne,
I have been using your script watchfile and it works great, but it always has to be running and I have to have a Terminal window open always. So I tried bubblegum, but I couldn't get it to work with directories and I emailed the developer and no response so far.

You don't need to run the 'watchfile' script in the foreground of a Terminal window. You can start any program in the background by adding an ampersand (&) at the end of the invocation command. If the program sends results to the terminal window (as 'watchfile' does) then you need to redirect the output into a file.

E.g. you could run the above example in the background as follows:
watchfile ~/Library/Preferences/com.apple.* > ~/myoutput &
where I have redirected the output into the file ~/myoutput
When you start a program in the background like this, it stays running even when the Terminal window is closed. In fact it will stay running until the machine is rebooted. You can examine the output file whenever you want. Doing it this way gives you something very much like what bubblegum does.

Thanks a bunch, I'm somewhat new to unix/linux. What happens if you dont redirect the output to a file and if there is eventually output, where does that output go or is there an error?

Also, if I were to run this script watchfile in the background as you described and quit the Terminal, how would I later on kill this process. Usually I use 'jobs' to find the currently running jobs, but this only applies to my current tty.
Thanks again for your help, I'm learning.

You can kill any process that you started if you know the process id (pid) by using the 'kill' command. You can find out the pid by using the command 'ps'.
Or if you know that there is only one instance of a process with a particular name, you can use 'killall'.
May I suggest that you should read some of the many freely available UNIX tutorials? There are some listed in the links section of this site.

I hope I did this correctly as I am new to perl. In my previous question I wanted to know if instead of notifying the user of changes, could it just do something else, like run a script? Well I digged around your script and this is what I changed (I hope this is ok under your terms?):
# print '$date: $filename: $msgn';
system('sh /home/paul/CreateIndex') if $show_info;
This now runs my script when a particular folder is updated. This is much better than a cron job that runs the script every 5 minutes even if the folder wasn't updated.

Of course there is no problem with you changing the script as you like. The license (Perl's 'Artistic License') allows you to do more or less whatever you want as long as you maintain the copyright notice and indicate what things you changed.

Your changes to the watchfile script (to make it invoke another script when a change is detected) seem like they will do what you want. You might want to enhance your shell script to handle command-line arguments and then you could pass it interesting information such as which file got changed.
E.g.:
system('/bin/sh /home/paul/CreateIndex $filename') if $show_info

Cool, I had not thought of that. I will make the change now. And thanks again for writing this script. I found another program in Linux that does almost what yours does and is called watch.

Macos Watch For File Changes Free

hi ,
Is it possibile to change script to send email to let say administrator everytime some files in folder are changed?
how?
br
Damjan

When I wrote the script, I hadn't considered using it to watch folders but I see that this can be useful too - e.g. pwharff's comment indicates that he is using it to monitor a folder for files added.

To make the script work better when used to watch folders, I would recommend changing the line that does the 'ls -l' to use 'ls -ld' instead. I.e. change it to:
system('/bin/ls -ld '$filename') if $show_info;
This will make it just list the info about the folder itself instead of listing all the files in that folder (which gets rather noisy if the folder contents change much). It will still give you the info for a file as before, so it's a win-win scenario.

In case you wanted to do something different with folders that have changed as opposed to files that have changed, you could test if $filename is a folder by using if (-d $filename)

What if I want to watch every file in the FS? Not gonna work to poll every file every 10 seconds or probably even every minute. It seems to me like the proper place for this would be the file system. I remember a utility a long time away (in an OS far far away) which would basically trap all system calls so you could see every change to the filesystem.
Why isn't Apple innovating and improving their file system? I know I've complained about Panther not having any DB stuff in the FS, maybe its time to start looking at Reiser 4, it should be out of alpha soon. (Now if only I could completely replace HFS+ with that...)

Interesting! Which method would be used under OS X - IMon, DNotify, kqueue, polling?

Hi,
Any body can provide me a prepared script that I can just copy and give execute permission to script for the purpose as mentioned below:
Checks the folder and send the mail to specified users for updates like
file or folder creation, deletion or change.
Thanks in advance for your help.
Best Regards,
Manoj Manchanda

I made a few improvements to the 'watchfile' script:

• better behaviour when the files being watched don't initially exist, or when they come and go
• option to watch for changes to the resource fork as well

The revised version is available here

Posted on January 13, 2019 by Paul

Updated 24 September 2019

In this article I will show you how to use the C++17 std::filesystem library to write a simple file watcher or file monitor. The advantage of using the C++17 std::filesystem library is that your code will be portable on all operating systems for which a C++17 compiler is available.

Macos Watch For File Changes Online

We are going to implement a C++17 file watcher that will monitor a given folder for file changes. For our limited purposes, we’ll monitor only the creation, modification and deletion of all files from the watched directory. The base folder will be checked for changes at regular time intervals and, in case of changes, we’ll run a user defined function.

Macos Watch For File Changes Online

Disclaimer: The code presented in this article is not meant to be used as is in production. The code was written as an exercise or demo to show what you can do with the C++17 std::filesystem library. If you want the ultimate performance, you should try to use the operating system functions like inotify on Linux or kqueue on macOS and FreeBSD.

At the time of this writing, you can use the C++17 std::filesystem library with GCC 9, Clang 7 and MSVC 2017. Here is an example of compiling a C++ program that uses std::filesystem with GCC:

Clang 8:

Clang 9 and up:

Please note that, at the time this writing, Apple’s Clang from Xcode 10 or the Command Line Tools doesn’t support the std::filesystem library. If you want to install GCC 9 on your macOS check this article.

Macos Watch For File Changes 2017

We’ll start by writing a FileWatcher class that will check a given folder for changes at regular intervals. Here is an example of how I want to be able to use our FileWatcher class:

Let’s start by defining the list of possible file changes (creation, modification, deletion) in FileWatcher.h:

Next, we can start writing the FileWatcher class. If we want to be able to monitor what file was changed, we’ll need a way to keep a record of the existing files in the watched folder. A simple approach is to use a hash table that will have as keys the file path and as values the time of the last modification of the file. We can use a std::unordered_map to store the above:

Now, we can implement the function that will start monitoring the base folder path_to_watch for changes:

Macos Watch For File Changes Windows 7

The start function will start an infinite loop in which we wait delay milliseconds and than we check for file changes. If a change is detected, we call the user defined action function that receives as parameters the file path, as a string, and the type of change detected.

Please note the contains function that checks if a given key is present in the paths_. The C++20 standard will add a contains member function to std::unordered_map, at which time you can replace line 28 from the above code with something like:

and remove our contains function.

At this point, FileWatcher.h is complete. Here is an example of using it to monitor the current folder for changes every five seconds:

In the above code, the user has supplied a lambda function that will be called when a file change is detected.

You can find the complete source code on the GitHub repository for this article.

Next, I will show you an example of building, running and testing the above code on my machine. I’ve used two Terminal windows, one for interacting with the program and one for file operations. Here is the first window output:

Second window output:

If you are interested to learn more about modern C++ I would recommend reading A tour of C++ by Bjarne Stroustrup.

Macos Watch For File Changes Full

or Effective Modern C++ by Scott Meyers.