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Operating System Tools

Notes Self Assessment

Fill in the blanks:
3. ........................................ are small applications that run on the Panel.

4. ........................................ allow the user a quick way to access specific resources on the
system.

2.3 The File System

A file system is defined as an organization of data and metadata on a storage device. With a
vague definition like that, you know that the code required to support this will be interesting.
Most files are just files, called regular files; they contain normal data.

Example: Text files, executable files or programs, input for or output from a program and
so on.
While it is reasonably safe to suppose that everything you encounter on a Linux system is a file,
there are some exceptions.
z z Directories: files that are lists of other files.
z z Special files: the mechanism used for input and output. Most special files are in /dev.

z z Links: a system to make a file or directory visible in multiple parts of the system’s file tree.
z z (Domain) sockets: a special file type, similar to TCP/IP sockets, providing inter-process
networking protected by the file system’s access control.

z z Named pipes: act more or less like sockets and form a way for processes to communicate
with each other, without using network socket semantics.
The-l option to ls displays the file type, using the first character of each input line:
/Documents> ls -l
total 80
-rw-rw-r-- 1 jaime jaime 31744 Feb 21 17:56 intro Linux.doc

-rw-rw-r-- 1 jaime jaime 41472 Feb 21 17:56 Linux.doc
drwxrwxr-x 2 jaime jaime 4096 Feb 25 11:50 course
This table gives an overview of the characters determining the file type:

Table 2.1: 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

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