File Types in Unix Based OSs

There are 7 types of files in a UNIX like environment:

1. Regular File
2. Directories
3. Character device files
4. Block device files
5. Local domain sockets
6. Named pipes(FIFOs)
7. Symbolic links

Determining File Types using ls

You can determine the file type of an existing file with ls -ld

• The flag -l displays detailed information about the file or directory like permission, number of links, owner, group, size etc.
• Flag -d prevents ls from listing the content of directories, instead it shows the information about the directory itself. For example:

$ ls -l /usr/man
total 12
drwxr-xr-x 2 root root 4096 Apr 10 16:42 man1
drwxr-xr-x 2 root root 4096 Apr 10 16:42 man3
drwxr-xr-x 2 root root 4096 Apr 10 16:42 man7

$ ls -ld /usr/man
drwxr-xr-x 5 root root 4096 Apr 10 16:42 /usr/man

File Type encoding Used by ls

Regular Files

• Regular files consist of a series of bytes.
• The filesystems impose no structure on their contents.
• Both sequential and random access is allowed.
• Example: Text files, data files, executable programs and shared libraries.

Directories

• A directory contains named references to other files.
• mkdir and rmdir is used to create and delete directories respectively.
• The special entries . and .. refer to the directory itself and its parent directory.
• A file's name is stored within its parent directory, not with the file itself.
• More than one file inside a directory