Hi, Can anyone tell what is the type of the file that we get after compiling a .C file and how do we find that ?
I used the gcc command to compile.
Ex:
gcc ex.c -o ex

And I new to linux so I don't know what is the extension. I am sure that is not .exe.
I used the following commands to find the type..

file *
file ex
ls
ls -l
ls -la

And I have another question. Can I encrypt a compiled c file? I know we can encrypt. But how do we decrypt that?
I encrypt that "ex" file. But I don't know how to decrypt.
We can decrypt the .txt file easily. But how to do that for a compiled file?

Thanks!!!

If you used the -o option with gcc, then it will be an ELF executable file you will get, if it compiled properly. Otherwise it will be an a.out file instead.

You would use the file command to see what type of any file is.

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Ok, But Why it showing ELF for a .TXT file?

A .exe file is a Windows executable file - Linux uses ELF executables. Executable files in Linux don't have any file extension on the end of them.

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Probably because you compiled it with the .txt file extension.

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Do you mean to say that the file includes .TXT at the end of its name? The name of the file has no relevance to the actual content. You can see the actual type using file as mentioned already and that you've listed yourself. Try:

Where "ex" is the name of the file in question.

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If you use the -o option that way the result does NOT have an extension, it will just plainly be called ex.
And it will be an ELF LSB executable, either 32-bit (if you're using a 32-bit distro) or 64-bit.

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They could have, but normally they don't, indeed.
But, i.e. scripts that are executable often have a .sh (shell script), .pl (perl script) or .py (Python) extension and sometime, when the binary is not meant to be used directly it could have a .bin extension (or -bin, see for instance firefox). The actual call is then through a script (like /usr/bin/firefox).

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Thnx brothers, I made a mistake, I said that the "file" command showing ELF Extension for a TXT file. It is showing, but that TXT file is a output of encrypted ELF file after decryption. So, sorry for that question. And tell me how to decrypt an encrypted ELF file using GnuPG?

You decrypt it by the opposite operation from the encrypt.
For instance if you used GnuPG with your PUBLIC key to encrypt, you use GnuPG again with your PRIVATE key to decrypt (as GPG is not symmetric, you always need "the other key" to do the opposite operation).
BTW: as you probably already discovered, encrypted executables can NOT be executed anymore.

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Thanks brother!!! I expected this reply "encrypted executables can NOT be executed anymore"