How to Find Out File Types in Linux

The easiest way to determine the type of a file on any operating system is usually to look at its extension (for instance .xml, .sh, .c, .tar etc..). What if a file doesn’t have an extension, how can you determine its type?

Read Also: 7 Ways to Find Out File System Types in Linux

Linux has a useful utility called file which carry out some tests on a specified file and prints the file type once a test is successful. In this short article, we will explain useful file command examples to determine a file type in Linux.

Note: To have all the options described in this article, you should be running file version 5.25 (available in Ubuntu repositories) or newer. CentOS repositories have an older version of file command (file-5.11) which lacks some options.

You can run following command to verify the version of file utility as shown.

$ file -v

file-5.33
magic file from /etc/magic:/usr/share/misc/magic

Linux file Command Examples

1. The simplest file command is as follows where you just provide a file whose type you want to find out.

$ file etc
Find File Type in Linux
Find File Type in Linux

2. You can also pass the names of the files to be examined from a file (one per line), which you can specify using the -f flag as shown.

$ file -f files.list
Find Files Type in Filename List
Find Files Type in Filename List

3. To make file work faster you can exclude a test (valid tests include apptype, ascii, encoding, tokens, cdf, compress, elf, soft and tar) from the list of tests made to determine the file type, use the -e flag as shown.

$ file -e ascii -e compress -e elf etc

4. The -s option causes file to also read block or character special files, for example.

$ file -s /dev/sda

/dev/sda: DOS/MBR boot sector, extended partition table (last)

5. Adding the -z options instructs file to look inside compressed files.

$ file -z backup
Determine Compressed Files
Determine Compressed Files

6. If you want to report information about the contents only not the compression, of a compressed file, use the -Z flag.

$ file -Z backup

7. You can tell file command to output mime type strings instead of the more traditional human readable ones, using the -i option.

$ file -i -s /dev/sda

/dev/sda: application/octet-stream; charset=binary

8. In addition, you can get a slash-separated list of valid extensions for the file type found by adding the –extension switch.

$ file --extension /dev/sda

For more information and usage options, consult the file command man page.

$ man file

That’s all! file command is a useful Linux utility to determine the type of a file without an extension. In this article, we shared some useful file command examples. If you have any questions or thoughts to share, use the feedback form below to reach us.

Aaron Kili
Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.

Each tutorial at TecMint is created by a team of experienced Linux system administrators so that it meets our high-quality standards.

Join the TecMint Weekly Newsletter (More Than 156,129 Linux Enthusiasts Have Subscribed)
Was this article helpful? Please add a comment or buy me a coffee to show your appreciation.

Got something to say? Join the discussion.

Thank you for taking the time to share your thoughts with us. We appreciate your decision to leave a comment and value your contribution to the discussion. It's important to note that we moderate all comments in accordance with our comment policy to ensure a respectful and constructive conversation.

Rest assured that your email address will remain private and will not be published or shared with anyone. We prioritize the privacy and security of our users.