There exist several Linux commands tailored for both beginners and experienced users, with the Linux file command being particularly noteworthy. This command plays a pivotal role in determining the type of data stored in a specific system file, presenting it in an understandable format, commonly known as a MIME type. In this tutorial, you will grasp the fundamentals of utilizing the Linux file command and understand how it can empower your VPS management.
UNIX filenames can be devoid of explicit file types, as the Linux file command effortlessly unveils this information. Whether it's an audio file, an open document spreadsheet, or a text editor file, the Linux file command aptly showcases its type in a readable format.
How to Use the Linux File Command?
The Linux file command serves various purposes, aiding in comprehending why users might face challenges reading a specific file on the system. Furthermore, it assists in identifying the types of folders, sockets, FIFOs (pipes), and block special files. Notably, only zero-length files in the Linux system are viewable by the File command.
Linux File Command Syntax
Before executing the command, ensure SSH access to your VPS. The basic syntax for the file command is outlined below:
file [options] [filename]
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file: Initiates the Linux file command.
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[options]: Allows the addition of variables to the command.
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[filename]: Represents the file you want to examine using the command.
Upon running the command, the system automatically responds, providing information about the file type in a standard output format. Additionally, you receive valuable details such as data stored in the file, file size, or the file version you specified.
As an example, consider a simple text.txt file. The most basic form of the Linux file command would be:
file test.txt
The output indicates that the file is an ASCII text file, demonstrating the utility and versatility of the Linux file command.
What to Utilize the Linux File Command For?
The Linux file command serves the purpose of analyzing each argument for classification. It conducts three sets of tests in sequence: file system tests, magic tests, and language tests. Upon successful analysis, it provides information about the file type.
File system tests involve users studying the return from a stat system call. The program checks if the file is clear or if it's a special type of file. It looks for known file types relevant to the system specified in the system header file.
Magic tests handle files with fixed data arrangements. Typically, a database is employed to probe lead bytes using the file command. Magic files, where this database is implemented, are located in devisers/file/magic or a similar directory. These files contain a magic number indicating to Linux and other operating systems that the file is a binary executable.
After determining the character set, the command attempts to specify the language in which the file is written. Language tests search for special sequences appearing anywhere in the first few segments of a file. While not as definitive as the previous two groups, these tests are conducted later.
Using the Linux File Command with Options
As UNIX filenames lack a connection with their file type, the file command proves invaluable. For example, a file named devisers.csv might be a zip file, which can be tested with the command:
file devisers.csv
To view only the file type, use the -b option in the terminal along with the filename:
file –b devisers.txt
The file command can operate on multiple files in the system, returning output on separate lines for each file. Use a wildcard (*) as a variable to analyze all .txt files in the current directory:
file *.txt
Details for all .txt files in the current directory will be shown.
To view the MIME type of a file in a non-readable format, use the -i option:
file –i devisers.csv
For viewing special files, use -s to read argument files not functioning or containing special characters. The command provides information about the size of special files. For instance:
file –s txt.t
Ensure to add the name of the actual file you want to inspect!
Summary
The Linux file command proves to be a versatile utility, offering diverse functionalities based on your needs. By specifying the file and using the command in the correct syntax, you can generate useful information about the contents on your machine. Familiarizing yourself with this command enables a deeper understanding of the various file types in your system, contributing to successful project development. Happy developing!