File Attributes in OS

Storing data is an essential component of using computers. We all store data in files. Whatever the type of files may be, we use files daily. While using files you also may have come across the ‘file attributes’. They are nothing but the characteristics of the file itself. File Attributes is an essential topic in Operating Systems. In this article, file, and file attributes are discussed.

What is a File?

We all know that we regularly store information on computers. Computers store this information on physical storage devices like disks. To use & retrieve this stored information conveniently, the operating system provides a structured mechanism (more technically, ‘logical view’) to store this information. Within this logical framework, the operating system organizes information at various levels of abstraction. ‘File’ is nothing but a logical storage unit of information. A file represents the smallest unit of allocation on logical secondary storage. We cannot store information on our computer unless we store it in files as it is the most basic level of storage.

The part of the operating system dealing with files is called the file system. The file system manages and organizes the files.

File Attributes

Each file has characteristics like file name, file type, date (on which file was created), etc. These characteristics are referred to as ‘File Attributes’. The operating system associates these attributes with files. In different operating systems files may have different attributes. Some people call attributes metadata also.

Following are some common file attributes:

1. Name: File name is the name given to the file. A name is usually a string of characters.
2. Identifier: Identifier is a unique number for a file. It identifies files within the file system. It is not readable to us, unlike file names.
3. Type: Type is another attribute of a file which specifies the type of file such as archive file (.zip), source code file (.c, .java), .docx file, .txt file, etc.
4. Location: Specifies the location of the file on the device (The directory path). This attribute is a pointer to a device.
5. Size: Specifies the current size of the file (in Kb, Mb, Gb, etc.) and possibly the maximum allowed size of the file.
6. Protection: Specifies information about Access control (Permissions about Who can read, edit, write, and execute the file.) It provides security to sensitive and private information.
7. Time, date, and user identification: This information tells us about the date and time on which the file was created, last modified, created and modified by which user, etc.

OS File Attributes

Some Other Attributes May Include:

Attributes related to flags. These Flags control or enable some specific property:

1. Read-only flag: 0 for read/write; 1 for read-only.
2. Hidden flag: 0 for normal; 1 for do not display in listings of all files.
3. System flag: 0 for normal files; 1 for system files.
4. Archive flag: 0 for has been backed up; 1 for needs to be backed up.
5. ASCII/binary flag: 0 for ASCII file; 1 for binary file.
6. Random access flag: 0 for sequential access only; 1 for random access.
7. Temporary flag: 0 for normal; 1 for deleted file on process exit.
8. Lock flags: 0 for unlocked; nonzero for locked.

Attribute related to keys. These are present in files which can be accessed using key:

1. Record length: Number of bytes in a record.
2. Key position: Offset of the key within each record.
3. Key length: Number of bytes in the key field.

Some file systems also support extended file attributes, such as character encoding of the file and security features such as a file checksum.

All above attributes are not present in all files. Files may posses different attributes as per the requirement. The attributes also varies from system to system. Attributes are also stored in secondary storage (File name and identifier are stored in directory structure. Identifier in turn locates other attributes). Attributes are important because they provide that extra information about the files which can be useful.

Conclusion

For effective management of files, attributes are given to the files. Attributes are nothing but the characteristics of the file like file name, file size, location of file etc. These attributes helps OS and users to use the files productively. Attributes includes File name, Identifier, size, location, type, protection (access control), date and time, user name, etc. These are some common attributes which may be present in all OS but there are some attributes which may vary from one OS to another. There are some dynamic attributes also which enables us to save changes in files. Ultimately, file attributes helps users and OS to optimize the work.

FAQs on OS File Attributes

Q.1: What is the significance of file attributes in an operating system?

Answer:

File attributes provide extra information about the file itself. This information such as author name, file creation date and time, file size, etc. is very essential as they help users and OS to use the files effectively. File attributes make user’s life easy because with the help of these attributes user can retrieve the files very easily.

Q.2: Can file attributes change over time?

Answer:

Yes, file attributes can change. There are some dynamic file attributes such as last modified date and time, name of user who modified the file, file size, etc. These and other attributes can change over time as per the requirement. For example, if we add some data to file, file size can increase. However, there are some static attributes that cannot change.

Q.3: How do file attributes provide security?

Answer:

File attributes play essential role in security of file. Attributes related to access control and permissions allow only authorized users to view and modify the file. This guarantees the protection of sensitive and private data in the file.

Q.4: Are file attributes the same across all operating systems?

Answer:

No, file attributes vary from operating system to operating system. All operating systems may provide some common attributes but some attributes can change. For example, one OS may provide the timestamp attribute while other may not.