As we all know that everything is a file in Linux, which includes Hard Disk, Graphics Card, etc.
When you are navigating to the Linux file system most of the files are fall under regular files and directories.
But it has other file types as well for different purpose. It has five types as per my knowledge.
So, it’s very important to understand the file types in Linux, that helps you in many ways.
In Linux, a file can use an extension, but the actual purpose may be different. Linux does not use file extensions, instead the file type is part of the file name.
If you can’t believe this, check out the full article to know how important it is.
To understand the color coding of Linux files go to the article below.
Make a note: Take a backup whenever you make any changes to the configuration file, as if you made the changes incorrectly, it could seriously damage your system, so be careful when you do this.
What Type of Files are Available in Linux
As per my knowledge, totally 7 types of files are available in Linux with 3 Major categories. The details are below.
- Regular File
- Directory File
- Special Files (There are five types of files in the special category)
- Link File
- Character Device File
- Socket File
- Named Pipe File
- Block File
Refer the below table for a better understanding of file types and their symbols in Linux.
+--------------+------------------------+ | Symbol | File Types | +--------------+------------------------+ | - | Regular File | | d | Directory | | l | Link File | | c | Character Device File | | s | Local Socket File | | p | Named Pipe File | | b | Block Device File | +--------------+------------------------+
Method-1: How to Identify File types in Linux Using the ls Command
The ls command helps you to identify and classify all kind of the file types found on a Linux system.
Regular file
The regular file is a common file type found everywhere on Linux system. These include text files, script files, images, binary files, and shared libraries,etc.
“-” This refers to the identification symbol for the regular file. You can use the rm command to remove a regular file.
# ls -la | grep ^- -rw-------. 1 mageshm mageshm 1394 Jan 18 15:59 .bash_history -rw-r--r--. 1 mageshm mageshm 18 May 11 2012 .bash_logout -rw-r--r--. 1 mageshm mageshm 176 May 11 2012 .bash_profile -rw-r--r--. 1 mageshm mageshm 124 May 11 2012 .bashrc -rw-r--r--. 1 root root 26 Dec 27 17:55 liks -rw-r--r--. 1 root root 104857600 Jan 31 2006 test100.dat -rw-r--r--. 1 root root 104874307 Dec 30 2012 test100.zip -rw-r--r--. 1 root root 11536384 Dec 30 2012 test10.zip -rw-r--r--. 1 root root 61 Dec 27 19:05 test2-bzip2.txt -rw-r--r--. 1 root root 61 Dec 31 14:24 test3-bzip2.txt -rw-r--r--. 1 root root 60 Dec 27 19:01 test-bzip2.txt
Directory
The directory is the second most common file type found on a Linux system. This can be created with the mkdir command.
# ls -la | grep ^d drwxr-xr-x. 3 mageshm mageshm 4096 Dec 31 14:24 links/ drwxrwxr-x. 2 mageshm mageshm 4096 Nov 16 15:44 perl5/ drwxr-xr-x. 2 mageshm mageshm 4096 Nov 16 15:37 public_ftp/ drwxr-xr-x. 3 mageshm mageshm 4096 Nov 16 15:37 public_html/
Link File
A link is a mechanism for creating a shortcut to the original file or directory. It contains information about another file or directory.
Links allow more than one filename to reference the same file.
There are two types of link files available, it’s soft link and hard link.
# ls -la | grep ^l lrwxrwxrwx. 1 root root 31 Dec 7 15:11 s-link-file -> /links/soft-link/test-soft-link lrwxrwxrwx. 1 root root 38 Dec 7 15:12 s-link-folder -> /links/soft-link/test-soft-link-folder
Character Device file
Character device files allow the user and application program to communicate directly with the hardware device. It’s not allow programs to read or write single characters at a time.
It is available under the /dev directory.
# ls -la | grep ^c crw-------. 1 root root 5, 1 Jan 28 14:05 console crw-rw----. 1 root root 10, 61 Jan 28 14:05 cpu_dma_latency crw-rw----. 1 root root 10, 62 Jan 28 14:05 crash crw-rw----. 1 root root 29, 0 Jan 28 14:05 fb0 crw-rw-rw-. 1 root root 1, 7 Jan 28 14:05 full crw-rw-rw-. 1 root root 10, 229 Jan 28 14:05 fuse
Block Device file
Block devices provide buffered access to hardware devices, it’s similar to character devices. Unlike character devices, block devices will always allow the programmer to read or write a block of any size at a time.
# ls -la | grep ^b brw-rw----. 1 root disk 7, 0 Jan 28 14:05 loop0 brw-rw----. 1 root disk 7, 1 Jan 28 14:05 loop1 brw-rw----. 1 root disk 7, 2 Jan 28 14:05 loop2 brw-rw----. 1 root disk 7, 3 Jan 28 14:05 loop3 brw-rw----. 1 root disk 7, 4 Jan 28 14:05 loop4
Socket file
A socket is a special file used for inter-process communication, which enables communication between two processes.
# ls -la | grep ^s
srw-rw-rw- 1 root root 0 Jan 5 16:36 system_bus_socket
Named Pipe file (FIFO)
a named pipe (also known as a FIFO) is one of the methods for inter-process communication.
Named pipes are special files that can exist anywhere in the file system. They can be created with the command mkfifo.
A named pipe is marked with a p as the first letter of the mode string.
# ls -la | grep ^p prw-------. 1 root root 0 Jan 28 14:06 replication-notify-fifo| prw-------. 1 root root 0 Jan 28 14:06 stats-mail|
Method-2: How to Identify File types in Linux Using the file Command
The file command allows you to determine various file types in Linux. There are three sets of tests will be performed against a file in the below order to identify the file types.
- Filesystem tests: Filesystem tests checks to see if the file is empty, or if it’s a special file. If the file type is found in the system header file, it is displayed as the correct file type.
- Magic Tests: Magic tests check the magic number stored in a specific location near the beginning of the file to determine the file type. Magic tests use the following files to match a file to its file type. The magic files are /usr/share/misc/magic.mgc, /usr/share/misc/magic and /etc/magic. If a file does not match any of the entries in the magic file, it is examined to see if it is a text file. If the file character set is reported like ASCII, ISO-8859-x, UTF-8, and extended-ASCII are identified as a ‘text’ file. UTF-16 and EBCDIC are text files, but translation will be required before reading them.
- Language Tests: Once the file type is determined as a text file. Language tests look for specific strings to determine in what language the file is written. It will appear anywhere in the first few blocks of a file. These tests are less reliable than the previous two tests, so they are performed last.
Regular file
Enter the file command on your terminal, followed by the regular file. The file command reads the contents of the given file and shows what kind of file it is.
That’s why you see below the different results for each regular file.
# file 2daygeek_access.log 2daygeek_access.log: ASCII text, with very long lines # file powertop.html powertop.html: HTML document, ASCII text, with very long lines # file 2g-test 2g-test: JSON data # file powertop.txt powertop.txt: HTML document, UTF-8 Unicode text, with very long lines # file 2g-test-05-01-2019.tar.gz 2g-test-05-01-2019.tar.gz: gzip compressed data, last modified: Sat Jan 5 18:22:20 2019, from Unix, original size 450560
Directory
# file Pictures/ Pictures/: directory
Link File
# file log log: symbolic link to /run/systemd/journal/dev-log
Character Device file
# file vcsu vcsu: character special (7/64)
Block Device file
# file sda1 sda1: block special (8/1)
Socket file
# file system_bus_socket system_bus_socket: socket
Named Pipe file
# file pipe-test pipe-test: fifo (named pipe)
Method-3: How to Identify File types in Linux Using the stat Command
The stat command allow us to check file types or file system status. This utility giving more information than file command.
It shows lot of information about the given file such as Size, Block Size, IO Block Size, Inode Value, Links, File permission, UID, GID, File Access, Modify and Change time details.
Regular files
# stat 2daygeek_access.log File: 2daygeek_access.log Size: 14406929 Blocks: 28144 IO Block: 4096 regular file Device: 10301h/66305d Inode: 1727555 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek) Access: 2019-01-03 14:05:26.430328867 +0530 Modify: 2019-01-03 14:05:26.460328868 +0530 Change: 2019-01-03 14:05:26.460328868 +0530 Birth: -
Directory
# stat Pictures/ File: Pictures/ Size: 4096 Blocks: 8 IO Block: 4096 directory Device: 10301h/66305d Inode: 1703982 Links: 3 Access: (0755/drwxr-xr-x) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek) Access: 2018-11-24 03:22:11.090000828 +0530 Modify: 2019-01-05 18:27:01.546958817 +0530 Change: 2019-01-05 18:27:01.546958817 +0530 Birth: -
Link file
# stat /dev/log File: /dev/log -> /run/systemd/journal/dev-log Size: 28 Blocks: 0 IO Block: 4096 symbolic link Device: 6h/6d Inode: 278 Links: 1 Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2019-01-05 16:36:31.033333447 +0530 Modify: 2019-01-05 16:36:30.766666768 +0530 Change: 2019-01-05 16:36:30.766666768 +0530 Birth: -
Character Device file
# stat /dev/vcsu File: /dev/vcsu Size: 0 Blocks: 0 IO Block: 4096 character special file Device: 6h/6d Inode: 16 Links: 1 Device type: 7,40 Access: (0660/crw-rw----) Uid: ( 0/ root) Gid: ( 5/ tty) Access: 2019-01-05 16:36:31.056666781 +0530 Modify: 2019-01-05 16:36:31.056666781 +0530 Change: 2019-01-05 16:36:31.056666781 +0530 Birth: -
Block Device file
# stat /dev/sda1 File: /dev/sda1 Size: 0 Blocks: 0 IO Block: 4096 block special file Device: 6h/6d Inode: 250 Links: 1 Device type: 8,1 Access: (0660/brw-rw----) Uid: ( 0/ root) Gid: ( 994/ disk) Access: 2019-01-05 16:36:31.596666806 +0530 Modify: 2019-01-05 16:36:31.596666806 +0530 Change: 2019-01-05 16:36:31.596666806 +0530 Birth: -
Socket file
# stat /var/run/dbus/system_bus_socket File: /var/run/dbus/system_bus_socket Size: 0 Blocks: 0 IO Block: 4096 socket Device: 15h/21d Inode: 576 Links: 1 Access: (0666/srw-rw-rw-) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2019-01-05 16:36:31.823333482 +0530 Modify: 2019-01-05 16:36:31.810000149 +0530 Change: 2019-01-05 16:36:31.810000149 +0530 Birth: -
Named Pipe file
# stat pipe-test File: pipe-test Size: 0 Blocks: 0 IO Block: 4096 fifo Device: 10301h/66305d Inode: 1705583 Links: 1 Access: (0644/prw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek) Access: 2019-01-06 02:00:03.040394731 +0530 Modify: 2019-01-06 02:00:03.040394731 +0530 Change: 2019-01-06 02:00:03.040394731 +0530 Birth: -
