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file Command in Linux

file Command in Linux

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Overview

In Linux, the file command is used to determine the type of a file. It can identify files based on their contents rather than relying on the file extension. This makes it a useful tool for identifying unknown or suspicious files. In this article, we'll cover the syntax, options, and usage of the file command, along with some tips and advanced usages.

Linux file Command Syntax

The syntax for the file command is as follows:

Where:

  • Options: The available options for the file command.
  • Filename: The name of the file to be analyzed by the file command.

file Command Options:

  • -b: Brief mode, displays the output in a compact format.
  • -i: MIME mode, outputs the MIME type of the file.
  • -z: Zero-terminated output, useful for scripting.

Example Usages

  • Display file type:

    Output:

    Explanation: This command displays the file type of 'myfile.txt' which is an ASCII text file.

  • Display file type in MIME format:

    Output:

    Explanation: This command displays the file type of 'myfile.jpg' in MIME format, which is an image/jpeg file.

Tips

  • The file command can be used to check if a file is corrupted or not.

  • The -b option can be used to display the output in a more readable format.

  • The file command works with any type of file, not just text files.

Advanced Use Cases of file Command in Linux

  • Display all files in a directory:

    Output:

    Explanation: This command displays the file types of all files in the current directory.

  • Identify shared libraries:

    Output:

    Explanation: This command identifies that '/usr/lib/libc.so.6' is a symbolic link to libc-2.28.so shared library.

  • Identify the architecture of an executable file:

    Output:

    Explanation: This command identifies the architecture of the executable file 'myprog' as 64-bit LSB, x86-64, and version 1 (SYSV). It also shows that the file is dynamically linked and not stripped of debug_info.

Conclusion

  • The file command is a powerful tool for identifying the type of a file based on its contents.

  • It can be used to identify unknown or suspicious files.

  • The command works with any type of file, not just text files.

  • The -b option can be used to display the output in a more readable format.

  • The -i option can be used to display the file type in MIME format.