It looks like all EXE files begin with MZ when they are opened in ASCII mode, is there an ASCII identified for vbs, com and bat files as well? i can't seem to find a pattern...
Or maybe there's another way to identify them? aside from just the extension...
No, not really (Windows executables can have PE or PK at the beginning instead of MZ - see this for other possible formats).
For other types of files, there are certain heuristics you can use (e.g. GIF files start with "GIF89", Bash shell scripts usually start with #!/bin/bash, BAT files often execute #echo off at the beginning, VBS scripts use apostrophe at the start of line as a comment marker), but they aren't always 100% reliable (a file can be both a BAT script and a Bash shell script; or a file that's both a valid ZIP archive and a valid GIF image (like that stegosaurus image), for example).
See e.g. this article for further reading.
TrID seems to have a "standalone" application you could probably use and pass the file in and read the contents out and see what file it is. It prides itself on the ability to pass it a generic file (extension or without) and it uses the headers of the file to discover what file type it actually is.
See if this tutorial is helpful (How to detect the types of executable files 3 part series). He has even presented a step by step algorithm on how to do this.
Also see this post: How to determine if a file is executable?
Related
I simply want to combine multiple eps files into one big file using gs command
the command work flawlessly except that when I specify more than 20 input files.
Somehow the command ignore input files starting from 21st input.
Anyone experience the same behavior? Is there a cap of number of input files specify anywhere?
I look through the site and couldn't find one.
sample command
gs -o output.eps -sDEVICE=eps2write file1.eps file2.eps .... file21.eps
Thank you.
Edit: add sample command
Almost certainly you have simply reached the maximum length of the command line for your Operating System. You can use the # syntax for Ghostscript to supply a file containing the command line instead.
https://www.ghostscript.com/doc/current/Use.htm#Input_control
Note that the EPS files will not be placed appropriately using that command, and this does not actually combine EPS files, it creates a new EPS file whose marking content should be the same as the input(s).
If you actually want to combine the EPS files its easy enough, but will require a small amount of programming to parse the EPS file headers and produce appropriate scale/translate operations, as well as stripping off any bitmap previews (which will also happen when you run them through Ghostscript).
Are there any rules for file extensions? For example, I wrote some code which reads and writes a byte pattern that is only understood by that specific programm. I'm assuming my anti virus programm won't be too happy if I give it the name "pleasetrustme.exe"... Is it gerally allowed to use those extensions? And what about the lesser known ones, like ".arw"?
You can use any file extension you want (or none at all). Using standard extensions that reflect the actual type of the file just makes things more convenient. On Windows, file extensions control stuff like how the files are displayed in Windows Explorer and what happens when you double click on it.
I wrote some code which reads and writes a byte pattern that is only
understood by that specific programm.
A file extension is only an indication of what type of data will be inside, never a guarantee that certain data formatted in a specific way will be inside the file.
For your own specific data structure it is of course always best to choose an extension that is not already in use for other file formats (or use a general extension like .dat or .bin maybe). This also has the advantage of being able to use an own icon without it being overwritten by other software using the same extension - or the other way around.
But maybe even more important when creating a custom (binary?) file format, is to provide a magic number as the first bytes of that file, maybe followed by a file header structure containing a version number etc. That way your own software can first check the header data to make sure it's the right type and version (for example: anyone could rename any file type to your extension, so your program needs to have a way to do some checks inside the file before reading the remaining data).
Seems like it must be easy, but I just can't figure it out. How do you delete the very last character of a file using Ruby IO?
I took a look at the answer for deleting the last line of a file with Ruby but didn't fully understand it, and there must be a simpler way.
Any help?
There is File.truncate:
truncate(file_name, integer) → 0
Truncates the file file_name to be at most integer bytes long. Not available on all platforms.
So you can say things like:
File.truncate(file_name, File.size(file_name) - 1)
That should truncate the file with a single system call to adjust the file's size in the file system without copying anything.
Note that not available on all platforms caveat though. File.truncate should be available on anything unixy (such as Linux or OSX), I can't say anything useful about Windows support.
I assume you are referring to a text file. The usual way of changing such is to read it, make the changes, then write a new file:
text = File.read(in_fname)
File.write(out_fname, text[0..-2])
Insert the name of the file you are reading from for in_fname and the name of the file you are writing to for 'out_fname'. They can be the same file, but if that's the intent it's safer to write to a temporary file, copy the temporary file to the original file then delete the temporary file. That way, if something goes wrong before the operations are completed, you will probably still have either the original or temporary file. text[0..-2] is a string comprised of all characters read except for the last one. You could alternatively do this:
File.write(out_fname, File.read(in_fname, File.stat(in_fname).size-1))
I need to write something that will read and execute all the files(Mainly executable scripts) inside one or more folders; in other words, a continuous chain with a break when finished. I'm new to shell and need syntax help. I'm on Ubuntu 12.10-Gnome btw.
Here are some main highlights I think should be included;
-The program should ask for one or more directories. Should process all the files given in these directories,
-Should create a .txt file on which files and folders are read and executed(for correction and informational purposes),
-Could contain a break option like control+shift+c maybe but thats clearly not of utmost importance.
The code, or the guidance to the code would be very much appreciated. Thx alot.
Does anyone know a pure Win32 solution for renaming a file and only changing its capitalization, that does not involve intermediate renaming to a different name or special privileges (e.g. backup, restore).
Since the Win32 subsystem generally regards two file names differing only in capitalization as the same, I haven't been able to find any solution to the problem.
A test program I made with the MoveFile API seems to work. So does the rename command in cmd.exe. What have you tried, and what error are you getting?
This isn't relevant, but further testing shows that renaming a long filename in this way works but will change the short filename (alternating between ~1 and ~2 for example), incidentally.
Just use the normal MoveFile API. That call probably just turns into ZwSetInformationFile(..., FileRenameInformation,...) The docs for FILE_RENAME_INFORMATION states that you need DELETE access and the file can't be locked etc, but those restrictions will probably apply to other solutions also.
I do not believe there is a way to expose two files with identical names that differ only in spelling to the Win32 subsystem. Even if some how you were able to create these files, the most likely result would be that only one file would be accessible - defeating the purpose of staying soley in Win32.
If you want to go into the Native layer, you can create a file with NtCreateFile and InitializeObjectAttributes w/o OBJ_CASE_INSENSITIVE or you can pad the end with extra spaces (if you pad with extra spaces, the file will not be accessible from Win32 dos paths). See here: http://www.osronline.com/ddkx/kmarch/k109_66uq.htm . I'm pretty sure you were already aware but I included it incase you did not know.
So long as your file is not immediately needed by another program, you can use my solution.
When you rename the file, capitalize, and delete the last letter. Then rename again and return the letter.
:)