How to Check a File Type in Linux
Use file to identify text, archives, executables and other file formats from the command line.
A filename extension is only a hint. Linux can inspect the bytes inside a file, and `file` is the standard quick way to ask what kind of data you actually have.
Step by step
1 Identify one file
$ file archive.tar.gzReports the detected file format and often additional details such as compression.
2 Check several files
$ file *Runs the same identification against each matching directory entry.
3 Check an executable
$ file /usr/bin/bashUseful for distinguishing architectures and executable formats.
4 Combine with extraction tools
$ file download && tar -tf downloadIdentify an archive before choosing the command that should process it.
Tips worth knowing
- Use `file` when an extension looks suspicious or a download fails to extract.
- It identifies content based on signatures and other heuristics; it is not a cryptographic authenticity check.
- Pair software downloads with checksums or signatures when available.
Frequently asked questions
How do I know what type a file is in Linux?
Run `file filename`.
Can file detect archives without extensions?
Usually yes; it can inspect known file signatures without relying on the filename extension.
Is file the same as MIME type?
Not exactly. `file --mime-type` can report a MIME type, while the normal output often gives a more descriptive classification.
The commands behind it
Create and extract archives: tar.gz, tar.bz2 — with the flag combinations finally explained.
sha256sum & md5sumFingerprint files, verify downloads, and prove two files are identical.
More how-to guides
See how much space is left, and find out what is using it.
Extract a .tar.gz archiveUnpack tar.gz, tar.bz2, tar.xz and zip archives from the command line.
Free a port that is already in useFind which process holds a port and stop it cleanly.
Find and replace text in filesReplace text in one file or across a whole project, safely.