Understanding type of files

Home

File types in a long list

Symbol	Meaning
-	Regular file
d	Directory
l	Link
c	Special file
s	Socket
p	Named pipe
b	Block device

Regular file

The regular file is a most common file type found on the Linux system. It governs all different files such us text files, images, binary files, shared libraries, etc. You can create a regular file with the touch command:

$ touch testfile.out

$ ls -ld testfile.out

-rw-rw-r-- 1 samual samual 0 Jan 10 12:52 testfile.out

The first character of the ls command, in this case "-", denotes the identification code for the regular file. Below command can be used to find out these type of files on system

$ find   /  -ls  |awk '{print $3, $NF}'  |grep ^-

To remove a regular file you can use the rm command:

$ rm testfile.out

Directory file

Directory is second most common file type found in Linux. Directory can be created with the mkdir command:

$ mkdir FileTypes

$ ls -ld FileTypes/

drwxrwxr-x 2 lubos lubos 4096 Jan 10 13:14 FileTypes/

Directory file can be identified by "d" symbol from the ls command output. Below command can be used to find out these type of files on system.

$ find   /  -ls  |awk '{print $3, $NF}'  |grep ^d

To remove empty  directory use the rmdir command.

$ rmdir FileTypes

When trying to remove directory with the rmdir command, which contains additional files you will get an error message:

rmdir: failed to remove `FileTypes/': Directory not empty

In this case you need to use a command:

$ rm -r FileTypes/

Character device file

Character device files allow users and programs to communicate with hardware peripheral devices. Terminal files are very easy example of such files.

The first character of the ls command, in this case "c", denotes the identification code for the character device file. Below command can be used to find out these type of files on system

$ find   /  -ls  |awk '{print $3, $NF}'  |grep ^c

Block device file

Block devices are similar to character devices. They mostly govern hardware as hard drives, memory, etc.

$ ls -ld /dev/sda

brw-rw---- 1 root disk 8, 0 Jan  4 10:12 /dev/sda

The first character of the ls command, in this case "b", denotes the identification code for the block device file. Below command can be used to find out these type of files on system

$ find / -ls |awk '{print $3, $NF}'  |grep ^b

Socket Files

Local domain sockets are used for communication between processes. Generally, they are used by services such as X windows, syslog and etc.

$ ls -ld /dev/log

srw-rw-rw- 1 root root 0 Jan  4 10:13 /dev/log

The first character of the ls command, in this case "b", denotes the identification code for the socket file. Below command can be used to find out these type of files on system

$ find   /  -ls  |awk '{print $3, $NF}'  |grep ^s

Sockets can be created by socket system call and removed by the unlink or rm commands.

Named pipe file

Similarly as Local sockets, named pipes allow communication between two local processes. They can be created by the mknod command and removed with the rm command.

The first character of the ls command, in this case "p", denotes the identification code for the named pipe file. Below command can be used to find out these type of files on system

$ find   /  -ls  |awk '{print $3, $NF}'  |grep ^l

Symbolic link file

With symbolic links an administrator can assign a file or directory multiple identities. Symbolic link can be a pointer to an original file. There are two types of symbolic links:

-          hard links

-          soft links

The difference between hard and soft links is that soft links use file name as reference and hard links use direct reference to the original file.  Furthermore, hard links cannot cross file systems and partitions. To create symbolic soft link we can use ln -s command:

$ echo file1 > file1

$ ln -s file1 file2

$ cat file2

file1

$ ls -ld file2

lrwxrwxrwx 1 lubos lubos 5 Jan 10 14:42 file2 -> file1

The first character of the ls command, in this case "l", denotes the identification code for the symbolic link file. Below command can be used to find out these type of files on system

$ find   /  -ls  |awk '{print $3, $NF}'  |grep ^l

To remove symbolic link we can use unlink or rm command.

Back To Top
Home