When writing to a binary file, when should I use .bin vs .dat? If I'm just trying to store information not meant to be read by humans, like item description/serial number pair, does it matter which one I pick if I'm just trying to make it unreadable from a text editor?
Let me give you some brief details about these files :
.BIN File : The BIN file type is primarily associated with 'Binary File'. Binary files are used for a wide variety of content and can be associated with a great many different programs. In general, a .BIN file will look like garbage when viewed in a file editor.
.DAT File : The DAT file type is primarily associated with 'Data'. Can be just about anything: text, graphic, or general binary data. Data file in special format or ASCII.
Reference:
Abhijit Banerjee answered that question on quora
.dat is a more frequently used suffix for binary data. It doesn't matter what extension you pick, as long as you are on Unix or Linux based systems.
Sufixes can mean whatever you want them to mean... Those rules are more like guidelines than actual rules...
However, BIN seems like a short to binary, so a BIN file will likely hold data in binary form. DAT seems like a short to data, so a DAT file will contain information in whatever format the developer of the program that reads that file seems fit (ASCII, Binary, a mix of them, something else entirely)
On a UNIX system, there is no difference. The extensions are interchangeable.
If you do not put any extension, it makes it kinda hard for someone not knowing what the file's extension should be, to open the file. Additionally, with Unix or Linux, if you place a dot (period) before the file name, the file hides itself.
Related
I have a file that holds manufacturing orders for a machine.
I would like to read the content of this file and edit it, but when I open it in a text editor i.e. Notepad++, I get a bunch of wierd charecters:
xÚ¥—_HSQÀo«a)’êaAXŽâê×pD8R‰¬©s“i+ƒ´#¡$
-þl-ó/ÓíºIúPôàƒHˆP–%a&RÎÈn÷ü¹·;Ú;ç<ìòÝÃý}¿ó}‡{϶«rWg>˜›ãR‡)Çn0³Ûf³yÎW[5–šw½ÇRW{ñ’rO6¹ŽŸp¦ÙœcÏ.9yÀnýg
)Ë—e90ejÕø£rC. f¦}3ËŒ˜hü”å1g[…ø±ú ÜJøz®‹˜YfÈ,4`ŽKÉ—ù“ÔË¿d„þlG3#=˜Ž´+hF¬¦£€«šm¿áØ
ïÖµv‡ËpíÍ~™‡Aù
šëÈÚ]ÿç™DŒÉFØ ïƒæsij ¦y=-74Æ/t=ÕŠr\˜š»Âä‰Ý¨žã΢
dz·à‡'fœ½yâ½4qåPjácòÄŒeÊhñ“ý™ÙÎÕ÷5ôlñ=˜Õ{ú;ø=Û;4OêYä>Ìpxbæâ'è"oëB×1gQ9“'¹]Ô³’Ô³ø!ÌózÞyŸõžÓIŽù*&OÌXPÕ"ŽWžpíOÌè‚Þ3Òr0{Ž†R=_?…/¼žÞ0,ê=/?£ûÓËîy“2Z<ij³[ËÁì™÷–ôžÎ’Ããa÷<Maêéí…¼ž}©žYýZ-˜=”á¤}π＞3°¢÷œ$ïè‰3ìž«ƒÄs¿—xnŒÀ*¯gi$ÕómDËÁìùIeоû‡À¬?3°x¾"~ª§c˜öÝÇî颌°›x¾Fßb>Ï}QXÓ{öFi-êÙßóR”œe^Ñ÷ü‘¿g[Lë ŽwJZϘë¹3”³L©gH‚,^Ïe 2ôžWGøëÙ2‚Î
øœL¾ÅqÈäõ,ýç\œË3¾þeྗ&`Ϻ<KÒf“’»ðù]í‰ãžU^wèþåÔÖy”H}ò•6ø6
It looks like the file is encoded.
Any idea how to find the encoding and make the file readable and editable?
It's binary and probably encoded so without knowledge of data structure you can't do much - just reverse engineering based on trying and checking what changed, operating with hex editor.
It isn't impossible, tho. If you can change the data the way you know (eg. change number of orders from 1 to 2) and export to file, you can compare binary values and find which byte holds that number. Of course if it is encrypted and you don't know the key... It's easier to find another way.
For further read, check this out - https://en.wikibooks.org/wiki/Reverse_Engineering/File_Formats
If you've got access to a Linux box why not use
hexdump -C <filename>
You will be able to get a much better insight into how the file is structured, than by using a text editor.
There are also many "hexdump" equivalent commands on Windows
As a general question: What's the role of file extension when determining file types?
For example, I can change .jpeg file to .png extension and even .txt. Of course, in the case of changing to .txt, it will neither be opened as picture, nor readable.
To determine file type, it seems the safe way is to parse the first few bytes of the file. If extension is not trustable, extension is no more than file name.
As a general rule, you should ALWAYS parse the COMPLETE file in order to be sure that the file is what the extension says. As you can easily imagine, it is pretty simple to create a binary file resembling a e.g. BMP (with a correct header) but then containing something different.
You should never trust the extension neither the header because otherwise a malicious user could exploit some of your code to generate e.g. a buffer overflow, and this is absolutely paramount if you are writing programs that must run at root/admin privilege.
Having said the obvious, the file extension nowadays is mainly used so that the OS can associate a program to that particular file (usually calling the program and passing the selected file as first parameter), and then it's up to the program to determine the file content.
It is a little bit different when talking about executable files. Under Unix, in order to be executable a file has to have the "x" flag set, otherwise it would not run, regardless of the extension. Under Windows, there is not such thing and the OS relies on only a few extensions (EXE, COM, BAT, etc.) to determine which files can be executed.
The EXE file, for example, has to start with "MZ" followed by some information for its allocation and size (http://www.delorie.com/djgpp/doc/exe/) and the OS surely checks its internal headers. Other formats (e.g. the COM executable format of the MS-DOS era) is just "pure" assembly code, so there is no check done by the OS. It just interprets those opcodes, hoping that everything will be fine.
So, to summarize:
File extension is mainly used so that the OS can call the appropriate program to open it (and passing the filename as the first parameter, argc/argv in C language for example)
Windows relies on some file extension to know if a file is executable, while Unix/Mac relies on a particular flag (x) associated with the file
Two things that are not well known about file extensions: directory names can have extension too, and extension can be way longer than the usual 3 characters.
With the help of file extension, you know how to read the first few and all the rest of the bytes. You also know what program to use to read the file. Or if it is an executable, you know that it is to be executed and not shown as a picture.
Yes you can change the file extension, but what does it mean then? It only means that OS (or any program that tried to read the file) is working correctly. Only you are providing bad data to it.
File extension is not something that some bytes of data inherently have. Extensions are given to those bytes depending upon the protocol followed to write them that way. After you have encoded the letters in binary form, you provide that binary form with .txt extension so that the text reader knows that these bytes convert to letters. That's the role of file extension. With bad file extension, this role is not fulfilled, resulting in incomprehension of the data you saved in binary.
As a general question: What's the role of file extension when determining file types?
The file extension usually identifies the application that opens a file.
If you rename a .JPG to a .PNG and while having JPG and PNG opened by the same application (usually an image viewer) that application can read the image stream and process it correctly regardless of having an incorrect file stream.
The problem arises if you rename the file in such a way that the file gets routed to an application that cannot handle the file's content.
If you rename a .DOCX (word) file to an Autocad extension (.DWG), opening the word file in autocad is likely to produce errors (unless per chance autocad can read word files).
I come to you completely stumped. I do some side work for a company that uses an old DOS based program to input and retrieve data. This is a legacy piece of software, and they have since moved to either QuickBooks or Outlook for all of their address or billing related needs. However there have been some changes made, and they work with this database fairly regularly. Since the computer that this software is on, is running XP (and none of the other computers in the office can run it) they're looking to phase this software out for when the computer inevitably explodes.
TLDR; I have an old .csv file (roughly two years) that has a good chunk of information on it, but again it's two years old. I have another file called ml.dat (I'm assuming masterlist.dat) that's in the same folder as this legacy software. I open it with notepad and excel and am presented with information like this:
S;Û).;PÃS;*p(â'a,µ,
The above chunk of text is recognized much less within notepad or excel. It's a lot more of the unrecognized squares.
Some of the information is actually readable however. I can for example read the occasional town name, or person's name but I'm unable to get all of the information since there's a lot missing. Perhaps the data isn't in unicode or something? I have no idea. Any suggestions? I'm ultimately trying to take this information and toss it into either quickbooks or outlook.
Please help!
Thanks
Edit: I'm guessing the file might be encrypted since .dat's are usually clear text? Any thoughts?
.DAT files can be anything, they are usually just application data. Since there is readable text, then it is very unlikely that this file is encrypted. Instead you are seeing ASCII representations of the bytes of other content. http://www.asciitable.com/ Assuming single byte values, the number 77 might appear in the file somewhere as M.
Your options:
Search for some utility to load and translate the dat file for that application.
Set up an appropriate dos emulator so you can run this application on another box, or even a virtual machine running freedos or something.
Figure out the file format and then write a program to translate the data.
For #3, you can attach a debugger to the application to trace how the file is read and written. Alternatively you can try to figure out record boundaries (if all the records are the same size, then things are a little bit easier.) Then you can use known values to try to find field boundaries. If you can find (or reverse compile) the source code, then that could also give you insight into the file format.
1 is your best bet, and #2 will buy you some time so that you don't need that original machine anymore. #3 would likely be something to outsource.
If you can find the source or file format, then you just recreate whatever data structure was dumped to the file and read the file into it.
To find which exe opens it, you can do something like:
for %f in (*.exe) do find "ml.dat" %f -c
Assuming the original application was written in C then there would be code something like this to read the first record from the file:
struct SecretData
{
int first;
double money;
char city[10];
};
FILE* input;
struct SecretData secretdata;
input = fopen("ml.dat", "rb");
fread(&data, sizeof(data), 1, input);
fclose(input);
(The file would have been written with fwrite.) Basically you need to figure out the innards of the SecretData structure to be able to read the file.
There likely wasn't a separate utility used to make the file, dumping data and reading it back from a file is relatively easy in most languages.
I am currently taking a curse in C programming, and for our final project we need to read some text from a pdf into a string, so we can manipulate the string.
In essence what i am looking for is something similar to this, only with a .pdf instead of a .txt file.
char *line;
fscanf(myfile.txt," %[^\n]", line);
I have no experience with ghostscript, so I have no idea if this is even possible, although we where told that we should use ghostscript.
The current version of Ghostscript includes the 'txtwrite' device, which will extract text from any supported input (PostScript, PDF, XPS, PCL) and will emit it in a variety of forms.
The UTF-8 output would probably be most useful to you.
Caveat! Many things which appear to be text in PDF files are not text, and no attempt is made to deal with these.
ps2ascii is deprecated with the release of the txtwrite device, but in any case its perfectly capable (despite the name) of dealing with PDF as an input.
I can't think why anyone assigned you this project, PDF files are not text files, and cannot be treated as such. In addition to the fact that PDF files are generally compressed, identifying the contents stream and all the other streams it relies on (which may themselves include text) is non-trivial. Plus, the text is often encoded in a way which can be difficult to understand (this is particularly true of CIDFonts and TrueType fonts).
Perhaps your tutor expected you to first become expert in the PDF format, but that seems excessive for a C course.
You can convert your PDF to Postscript using pdf2ps, and then to ASCII using ps2ascii. You already know how to read ASCII.
Both utilities mentioned are in the ghostscript package.
Is there any way to decode a PICS Rules File?
Contains settings and preferences used by the Windows operating system.
The file is given by:
Q:F]9y3n5|dp:n4hU)qbs;!&-bzh
The PICSRules spec defines what PICS rules should look like. I don't think your file is one of those.
Is that the entire file contents above?
Are you sure that it's definitely a PICS rules file? There are many file types which use the .prf extension, perhaps it's one of those.