Ubuntu – How to open a .bak file on Linux

filesfilesystemslinuxUbuntu

I have received a file of .bak format, let it be foo.bak. I don't know if it is a MS-DOS file or Linux/Unix file. What I know is that I can't open it because my Linux (Ubuntu) does not give any hint how to open it.

So, how I open this file?

Just to omit warnings about not knowing what I am doing:

Disclaimer: I received my file from a known place, it is not a virus. It is a soft copy of one system I should next work on. I just do not happen to know how to open it.

Best Answer

.bak generally designates that the file is a backup copy of something, but other than that it gives preciously little information as to the actual file type.

Try looking at the output of the file command, which studies the first few bits of the file to see if it recognizes it as a known filetype:

caleburn: ~/ >file image001.jpg 
image001.jpg: JPEG image data, JFIF standard 1.01
caleburn: ~/ >file oops.png 
oops.png: PNG image data, 935 x 546, 16-bit/color RGB, non-interlaced
caleburn: ~/ >file zones.zip 
zones.zip: Zip archive data, at least v2.0 to extract
caleburn: ~/ >file eth2.pcap 
eth2.pcap: tcpdump capture file (little-endian) - version 2.4 (Ethernet, capture length 96)

And so on, and so on. Once you know what type of file linux thinks it is, google should be able to suggest how to access it.

... Alternately, you can ask whoever sent it to you what the original filename was supposed to be and find out that way. :)

Related Solutions

Linux – Inspect Directory Structure Information

The simple answer is that what you want to do is to read the directory file, with a command like cat ., cat /etc, or cat mydir. Of course, since this is “raw” data, you’d want to use a program that’s better suited to displaying non-ASCII data in a human-friendly way; e.g., hexdump or od.

Unfortunately, as discussed in When did directories stop being readable as files?, most versions of Unix that were released in the past two decades or so don’t allow this. So the answer to your question may be “find a version of Unix that still allows reading directories”. AIX, most versions of BSD, and all but the most recent versions of Solaris may qualify. Finding a Linux that allows it may require the use of a time machine.

Linux – GNU nano 2: DOS Format or Mac Format on Linux

Use neither: enter a filename and press Enter, and the file will be saved with the default Unix line-endings (which is what you want on Linux).

If nano tells you it’s going to use DOS or Mac format (which happens if it loaded a file in DOS or Mac format), i.e. you see

File Name to Write [DOS Format]:

File Name to Write [Mac Format]:

press AltD or AltM respectively to deselect DOS or Mac format, which effectively selects the default Unix format.

Best Answer

Related Solutions

Linux – Inspect Directory Structure Information

Linux – GNU nano 2: DOS Format or Mac Format on Linux

Related Question