How to check if files are binaries?

jpollard · 02-09-2016, 08:19 PM

If you really want to know how files are identified, refer to the "magic(5)" man page...

I believe on most systems the file referenced for the definitions is at /usr/share/misc/magic.
There are some 14,000 different kinds of files identified.

BW-userx · 02-11-2016, 08:35 AM

you can do somthing as simple as open them up as a text file and if all you see is ununderstandable text then chances are it is a binary.

jpollard · 02-11-2016, 09:49 AM

Quote:

Originally Posted by BW-userx

you can do somthing as simple as open them up as a text file and if all you see is ununderstandable text then chances are it is a binary.

Ouch... no.

You are assuming the text is based in the Latin-1 character set...

Chinese uses multi-byte characters for everything - guess what? it is still a text file, even though it is not understandable by westerners.

BW-userx · 02-11-2016, 10:58 AM

Quote:

Originally Posted by jpollard

Ouch... no.

You are assuming the text is based in the Latin-1 character set...

Chinese uses multi-byte characters for everything - guess what? it is still a text file, even though it is not understandable by westerners.

damn Chinese think of everything -- Keepin us damn westerners confused ..

good job!

malekmustaq · 02-11-2016, 12:24 PM

Quote:

The purpose of it is to understand a bloody question I was asked on a test,

I thought we were solving an applied real-user problem.

Quote:

which was to delete all files that are not binaries going through 3 folders and making sure everything else is still in place.

a recursive "while...do..else" script can do that, by first acting on easily identifiable non-binary files having filename extension: tgz, gz, zip, odt, etc. Then test the remaining files by "strings", "file" or "grep" and act on them appropriately.

Quote:

Also to search inside the files and check if they have text inside containing "password" or "CONFIDENTIAL" and delete the ones that have CONFIDENTIAL text in them.

This is naive. $PASSWDs are normally encrypted and decryption is the antidote... something that could be unwieldy for a neophyte to handle in automation by script; you will need an expert for this. Though, if the strings "password" or "confidential" are the targets they are easily handled by "grep", or else, you can "hex" it --use a hex-editor there are plenty in the FOSS repositories.

Hope that helps. Good luck.