Server Administration 2

Linux

Basic Linux Concepts

Linux Kernel

Linux has a clear separation between user and kernel portions. Only essential features inside Operating Systems.

Processes are unit of scheduling and protection. Editors, command interpreters (“Shell), compilers, etc. are just processes.

All I/O looks like operations on files, ie. in Linux, everything is a file.

Files in Linux

File as an unstructure sequence of bytes. Files are represented in user-space by a file descriptor (fd) which is just an opaque identifier for ensuring protection between user and kernel. Kernel keeps track of the current position within the file. Devices are represented by special files

Read more: Everything in Linux is a file

File Operations

Operations on files are:


fd = open(pathname, mode)
fd = creat(pathname, mode)
bytes = read(fd, buffer, nbytes)
count = write(fd, buffer, nbytes)
reply = seek(fd, offset, whence)
reply = close(fd)

Linux Programming Concepts

Introduction to system programming; debugging; C review Data types, bit models, bitwise operators


Arrays, strings, memory map
String functions, command line arguments
Pointers
Structures; mixing arrays, structures and pointers

program building
Streams, devices
System calls;
program organization
System calls (processes); IPC (signals)
math library, Curses library;
blocking, buffering, echoing (I/O)
X library; events, graphics context
Software licenses

Linux Interprocess Communications (IPC)

Linux Headers

POSIX Basics

Linux Access Rights

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