I use various 3rd party libraries to convert files on my Linux server. For instance, ImageMagick/convert for images, libreoffice3.5/convert-to for Microsoft Office documents, etc.
Is it possible that these applications require the pre-converted file to have the proper extension for the type of file? For instance, if the file was a png file, it would need to be called whatever.png and not just whatever.
Thank you
your question sounds general, and in general linux apps do not require extensions. bash will execute a .png file with shell commands happily and vi will open a text file called a.exe. extensions are in general not a unix/linux concept to begin with and . is just an allowed character in the file name.
this being said, some particular application may interpret or even require correct extensions.
Related
I am working on a web app project to block all the file executable from file upload.
Example: user can upload, txt, png, image and video files and not any executable scripts like, Perl, Python, exe, PHP, .so, .sh files.
If it is a PHP file, then I strstr for "<?php" tag, If this tag is present, then it is PHP file. How can we find the same for other script/executable files?
Edit: Some time hackers will upload the malicious files using .png or .jpg extn, so what is the pattern to check inside the files?
Rather than making your own checks you make use of an existing library and you block everything that does not register as a desired format.
Most such libraries guess the content type and encoding of a file by looking for certain signatures or magic byte sequences at specific positions within the file.
Other libraries may be more specialised and will for example only identify image or video formats.
https://www.php.net/manual/en/intro.fileinfo.php
https://github.com/ahupp/python-magic
https://docs.python.org/3/library/imghdr.html
The file programme is a command line tool for identification of file types.
After the first pass where you identify and accept only the desired file formats you should then make all files that are not rejected go through an antivirus scanner.
Depending on you use cases you may decide to strip the original file name extension and/or even the complete file name that was provided during the upload and assign the mime-type that was detected rather than rely on user provided properties.
my friends
I have a question about why file extensions are created?
I found a quote on Wikipedia
"They are commonly used to imply information about the way data might be stored in the file"
what does it mean?
File extension is an identifier which tell the operating system what kind of data and file type they are working with and what associated program opens the file.
if u have an .apk extension file, system can easily recognize it as an application file. If it is an mp4, means it's some kind of multimedia file and can be operated with multimedia applications.
They are commonly used to imply information about the way data might be stored in the file. A normal text editor uses .txt as extension when an html uses extension .html These two files stores data differently.
While using linux system I encounter that that many file extensions are in capital as well as small letters like
myfile.JPG and myfile.jpg
I know Linux file system is case sensitive, but what's the difference in these two files? and why sometimes they get saved saved as capital or sometimes in small.
I have seen the same for other file too like
.ttf vs .TTF
Thanks
There is no difference if you name the file myfile.jpg or myfile.JPG or myfile.jpeg. Linux doesn't care.
The extension might be used by some programs running on linux and by humans to easily identify the filetype but it doen't affects the file in any way. You can even call it myfile.dog or just leave it without extension and would be the same image file and for linux it wouldn't make any difference.
If you have an image file and you want to tell what kind of image file it is you can use the file command or if you have imagemagick installed you can use the identify command.
Try renaming some jpeg file and give it a png extension, the run file image.png, you will see that it still is a jpeg file and that the png extension is there only to confuse you.
You might find this usefull: https://www.quora.com/How-do-Linux-identify-file-types-without-extensions-And-why-cant-Windows-do-so
Basically I am trying to get list of programs in Linux which are installed and can open particular file extension .jpg for example. If not all, At-least default program should get listed.
Linux (the kernel) has no knowledge on file types to application mapping. If you want to use Gnome programs you can look at https://people.gnome.org/~shaunm/admin-guide/mimetypes-7.html. For KDE there is another mechanism. Each toolkit can define it as it likes. And the programmer can use the defaults or not. So it is simply application specific!
What do you want to achieve?
If you (double) click with a explorer/browser application on an icon or file name, exactly the explorer/browser looks for the file type. Typically this is realized via mime type dictionary. But how a program looks for the file type and maybe execute another program is only related to the programmer who writes that program. The GUI tool-chains like Gnome and KDE have a lot of support for that topic and so you have basic conformity for each family of applications.
If you want to know how a application do the job, start it with strace. But it is quite hard to dig into the huge amount of data.
Also you can take a look for xdg-open. Many programs use this helper to start applications. As an example: If you start Dolphin with strace you will find a line like lstat64("/etc/xdg", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 after clicking on a file.
you can run from command line with:
xdg-open <file-name>
You maybe also want to have a look for applications which registers for file types: /usr/share/applications/*.desktop
Here you can find in each desktop file some mime-types which are registered for the applications. E.g. for audiacity is:
MimeType=application/x-audacity-project;audio/flac;audio/x-flac;audio/basic;audio/x-aiff;audio/x-wav;application/ogg;audio/x-vorbis+ogg;
For your example with jpg:
$ xdg-mime query filetype <any-jpg-file>
image/jpeg
$ grep 'image/jpeg' -R /usr/share/applications/*
...
/usr/share/applications/mimeinfo.cache:image/jpeg2000=kde4-kolourpaint.desktop;gimp.desktop;
So you can see that gimp is one of the default applications for jpg
The place to start looking is at the mailcap (/etc/mailcap) and MIME-types, e.g., in /etc/mime.types in Debian (the filename and path will vary according to who provides it).
The mailcap file gives some rules for opening a file, while MIME-types lists the known filetypes with a tag that allows multiple applications to know about the file types.
Except for embedded or reduced-functionality systems (such as those based on busybox), you would find these files on almost every UNIX-like system.
is it possible to change text and images in a fla file without ever opening it up and then making the swf via command line? I want to make a flash template and save the fla. Then be able to update my text and image name and convert it to swf. I have one template but tons of different text options and background images. It would be nice to be able to copy the master.fla twenty times and just change the source code (will do this from command line) and then convert to swf (via command line).
Any help would be appreciated.
With CS5, you can do half of what you're asking today, by using the XFL file format instead of FLA. Instead of a binary blob, you get an editable XML file and a tree of separate asset files: PNGs, AS3 files, etc. You can then modify the XML or AS3 files programmatically to get your variants.
(A CS5 FLA file is really just a zipped up version of the XFL, but there's no advantage to using that instead of an XFL. In CS4 and previous, FLA was a proprietary binary format.)
The missing piece is an XFL compiler. Adobe currently provides no such thing, and the third party market hasn't yet produced one.
You could use a systems automation tool to drive the Flash Professional environment through the compilation steps. On OS X, for example, either Automator or AppleScript should be able to do what you want. It'll just have more overhead than the command line compiler you were hoping for.
I agree with Jason, there are a lot of alternatives to what you suggest. Keeping content out of the SWF is good practice actually. This is a good way to avoid large files!
Depending on what you 're looking to achieve, there are a lot of solutions available. XML is an option, JSON another.
If you're looking to build a template, any of the above would seem appropriate.
It sounds like you're working from the Flash IDE, as Jason suggests you may want to have a look at another IDE, such as FlashDevelop, FDT or FlashBuilder as they make coding with AS3 a lot easier.