Shell — Temporarily Invoke Operating System
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The Linux Kernel Module Programming Guide
The Linux Kernel Module Programming Guide Peter Jay Salzman Michael Burian Ori Pomerantz Copyright © 2001 Peter Jay Salzman 2007−05−18 ver 2.6.4 The Linux Kernel Module Programming Guide is a free book; you may reproduce and/or modify it under the terms of the Open Software License, version 1.1. You can obtain a copy of this license at http://opensource.org/licenses/osl.php. This book is distributed in the hope it will be useful, but without any warranty, without even the implied warranty of merchantability or fitness for a particular purpose. The author encourages wide distribution of this book for personal or commercial use, provided the above copyright notice remains intact and the method adheres to the provisions of the Open Software License. In summary, you may copy and distribute this book free of charge or for a profit. No explicit permission is required from the author for reproduction of this book in any medium, physical or electronic. Derivative works and translations of this document must be placed under the Open Software License, and the original copyright notice must remain intact. If you have contributed new material to this book, you must make the material and source code available for your revisions. Please make revisions and updates available directly to the document maintainer, Peter Jay Salzman <[email protected]>. This will allow for the merging of updates and provide consistent revisions to the Linux community. If you publish or distribute this book commercially, donations, royalties, and/or printed copies are greatly appreciated by the author and the Linux Documentation Project (LDP). -
Writing Your First Linux Kernel Module
Writing your first Linux kernel module Praktikum Kernel Programming University of Hamburg Scientific Computing Winter semester 2014/2015 Outline ● Before you start ● Hello world module ● Compile, load and unload ● User space VS. kernel space programing ● Summary Before you start ● Define your module’s goal ● Define your module behaviour ● Know your hardware specifications ○ If you are building a device driver you should have the manual ● Documentation ○ /usr/src/linux/Documentation ○ make { htmldocs | psdocs | pdfdocks | rtfdocks } ○ /usr/src/linux/Documentation/DocBook Role of the device driver ● Software layer between application and device “black boxes” ○ Offer abstraction ■ Make hardware available to users ○ Hide complexity ■ User does not need to know their implementation ● Provide mechanism not policy ○ Mechanism ■ Providing the flexibility and the ability the device supports ○ Policy ■ Controlling how these capabilities are being used Role of the device driver ● Policy-free characteristics ○ Synchronous and asynchronous operations ○ Exploit the full capabilities of the hardware ○ Often a client library is provided as well ■ Provides capabilities that do not need to be implemented inside the module Outline ● Before you start ● Hello world module ● Compile, load and unload ● User space VS. kernel space programing ● Summary Hello world module /* header files */ #include <linux/module.h> #include <linux/init.h> /* the initialization function */ /* the shutdown function */ static int __init hello_init(void) { static void __exit hello_exit(void) -
Windows Command Prompt Cheatsheet
Windows Command Prompt Cheatsheet - Command line interface (as opposed to a GUI - graphical user interface) - Used to execute programs - Commands are small programs that do something useful - There are many commands already included with Windows, but we will use a few. - A filepath is where you are in the filesystem • C: is the C drive • C:\user\Documents is the Documents folder • C:\user\Documents\hello.c is a file in the Documents folder Command What it Does Usage dir Displays a list of a folder’s files dir (shows current folder) and subfolders dir myfolder cd Displays the name of the current cd filepath chdir directory or changes the current chdir filepath folder. cd .. (goes one directory up) md Creates a folder (directory) md folder-name mkdir mkdir folder-name rm Deletes a folder (directory) rm folder-name rmdir rmdir folder-name rm /s folder-name rmdir /s folder-name Note: if the folder isn’t empty, you must add the /s. copy Copies a file from one location to copy filepath-from filepath-to another move Moves file from one folder to move folder1\file.txt folder2\ another ren Changes the name of a file ren file1 file2 rename del Deletes one or more files del filename exit Exits batch script or current exit command control echo Used to display a message or to echo message turn off/on messages in batch scripts type Displays contents of a text file type myfile.txt fc Compares two files and displays fc file1 file2 the difference between them cls Clears the screen cls help Provides more details about help (lists all commands) DOS/Command Prompt help command commands Source: https://technet.microsoft.com/en-us/library/cc754340.aspx. -
Name Synopsis Description
Perl version 5.10.0 documentation - vmsish NAME vmsish - Perl pragma to control VMS-specific language features SYNOPSIS use vmsish; use vmsish 'status';# or '$?' use vmsish 'exit'; use vmsish 'time'; use vmsish 'hushed'; no vmsish 'hushed'; vmsish::hushed($hush); use vmsish; no vmsish 'time'; DESCRIPTION If no import list is supplied, all possible VMS-specific features areassumed. Currently, there are four VMS-specific features available:'status' (a.k.a '$?'), 'exit', 'time' and 'hushed'. If you're not running VMS, this module does nothing. vmsish status This makes $? and system return the native VMS exit statusinstead of emulating the POSIX exit status. vmsish exit This makes exit 1 produce a successful exit (with status SS$_NORMAL),instead of emulating UNIX exit(), which considers exit 1 to indicatean error. As with the CRTL's exit() function, exit 0 is also mappedto an exit status of SS$_NORMAL, and any other argument to exit() isused directly as Perl's exit status. vmsish time This makes all times relative to the local time zone, instead of thedefault of Universal Time (a.k.a Greenwich Mean Time, or GMT). vmsish hushed This suppresses printing of VMS status messages to SYS$OUTPUT andSYS$ERROR if Perl terminates with an error status. and allowsprograms that are expecting "unix-style" Perl to avoid having to parseVMS error messages. It does not suppress any messages from Perlitself, just the messages generated by DCL after Perl exits. The DCLsymbol $STATUS will still have the termination status, but with ahigh-order bit set: EXAMPLE:$ perl -e"exit 44;" Non-hushed error exit%SYSTEM-F-ABORT, abort DCL message$ show sym $STATUS$STATUS == "%X0000002C" $ perl -e"use vmsish qw(hushed); exit 44;" Hushed error exit $ show sym $STATUS $STATUS == "%X1000002C" The 'hushed' flag has a global scope during compilation: the exit() ordie() commands that are compiled after 'vmsish hushed' will be hushedwhen they are executed. -
A Concurrent PASCAL Compiler for Minicomputers
512 Appendix A DIFFERENCES BETWEEN UCSD'S PASCAL AND STANDARD PASCAL The PASCAL language used in this book contains most of the features described by K. Jensen and N. Wirth in PASCAL User Manual and Report, Springer Verlag, 1975. We refer to the PASCAL defined by Jensen and Wirth as "Standard" PASCAL, because of its widespread acceptance even though no international standard for the language has yet been established. The PASCAL used in this book has been implemented at University of California San Diego (UCSD) in a complete software system for use on a variety of small stand-alone microcomputers. This will be referred to as "UCSD PASCAL", which differs from the standard by a small number of omissions, a very small number of alterations, and several extensions. This appendix provides a very brief summary Of these differences. Only the PASCAL constructs used within this book will be mentioned herein. Documents are available from the author's group at UCSD describing UCSD PASCAL in detail. 1. CASE Statements Jensen & Wirth state that if there is no label equal to the value of the case statement selector, then the result of the case statement is undefined. UCSD PASCAL treats this situation by leaving the case statement normally with no action being taken. 2. Comments In UCSD PASCAL, a comment appears between the delimiting symbols "(*" and "*)". If the opening delimiter is followed immediately by a dollar sign, as in "(*$", then the remainder of the comment is treated as a directive to the compiler. The only compiler directive mentioned in this book is (*$G+*), which tells the compiler to allow the use of GOTO statements. -
Introduction to UNIX at MSI June 23, 2015 Presented by Nancy Rowe
Introduction to UNIX at MSI June 23, 2015 Presented by Nancy Rowe The Minnesota Supercomputing Institute for Advanced Computational Research www.msi.umn.edu/tutorial/ © 2015 Regents of the University of Minnesota. All rights reserved. Supercomputing Institute for Advanced Computational Research Overview • UNIX Overview • Logging into MSI © 2015 Regents of the University of Minnesota. All rights reserved. Supercomputing Institute for Advanced Computational Research Frequently Asked Questions msi.umn.edu > Resources> FAQ Website will be updated soon © 2015 Regents of the University of Minnesota. All rights reserved. Supercomputing Institute for Advanced Computational Research What’s the difference between Linux and UNIX? The terms can be used interchangeably © 2015 Regents of the University of Minnesota. All rights reserved. Supercomputing Institute for Advanced Computational Research UNIX • UNIX is the operating system of choice for engineering and scientific workstations • Originally developed in the late 1960s • Unix is flexible, secure and based on open standards • Programs are often designed “to do one simple thing right” • Unix provides ways for interconnecting these simple programs to work together and perform more complex tasks © 2015 Regents of the University of Minnesota. All rights reserved. Supercomputing Institute for Advanced Computational Research Getting Started • MSI account • Service Units required to access MSI HPC systems • Open a terminal while sitting at the machine • A shell provides an interface for the user to interact with the operating system • BASH is the default shell at MSI © 2015 Regents of the University of Minnesota. All rights reserved. Supercomputing Institute for Advanced Computational Research Bastion Host • login.msi.umn.edu • Connect to bastion host before connecting to HPC systems • Cannot run software on bastion host (login.msi.umn.edu) © 2015 Regents of the University of Minnesota. -
Lab - Observing DNS Resolution (Instructor Version) Instructor Note: Red Font Color Or Gray Highlights Indicate Text That Appears in the Instructor Copy Only
Lab - Observing DNS Resolution (Instructor Version) Instructor Note: Red font color or Gray highlights indicate text that appears in the instructor copy only. Objectives Part 1: Observe the DNS Conversion of a URL to an IP Address Part 2: Observe DNS Lookup Using the Nslookup Command on a Web Site Part 3: Observe DNS Lookup Using the Nslookup Command on Mail Servers Background / Scenario The Domain Name System (DNS) is invoked when you type a Uniform Resource Locator (URL), such as http://www.cisco.com, into a web browser. The first part of the URL describes which protocol is used. Common protocols are Hypertext Transfer Protocol (HTTP), Hypertext Transfer Protocol over Secure Socket Layer (HTTPS), and File Transfer Protocol (FTP). DNS uses the second part of the URL, which in this example is www.cisco.com. DNS translates the domain name (www.cisco.com) to an IP address to allow the source host to reach the destination host. In this lab, you will observe DNS in action and use the nslookup (name server lookup) command to obtain additional DNS information. Work with a partner to complete this lab. Required Resources 1 PC (Windows 7, Vista, or XP with Internet and command prompt access) Part 1: Observe the DNS Conversion of a URL to an IP Address a. Click the Windows Start button, type cmd into the search field, and press Enter. The command prompt window appears. b. At the command prompt, ping the URL for the Internet Corporation for Assigned Names and Numbers (ICANN) at www.icann.org. ICANN coordinates the DNS, IP addresses, top-level domain name system management, and root server system management functions. -
Shell Code for Beginners
Shell Code For Beginners Beenu Arora Site: www.BeenuArora.com Email: [email protected] ################################################################ # .___ __ _______ .___ # # __| _/____ _______| | __ ____ \ _ \ __| _/____ # # / __ |\__ \\_ __ \ |/ // ___\/ /_\ \ / __ |/ __ \ # # / /_/ | / __ \| | \/ <\ \___\ \_/ \/ /_/ \ ___/ # # \____ |(______/__| |__|_ \\_____>\_____ /\_____|\____\ # # \/ \/ \/ # # ___________ ______ _ __ # # _/ ___\_ __ \_/ __ \ \/ \/ / # # \ \___| | \/\ ___/\ / # # \___ >__| \___ >\/\_/ # # est.2007 \/ \/ forum.darkc0de.com # ################################################################ What is a shell Code? Shellcode is defined as a set of instructions injected and then executed by an exploited program. Shellcode is used to directly manipulate registers and the functionality of a exploited program. We can of course write shell codes in the high level language but would let you know later why they might not work for some cases, so assembly language is preferred for this. I would take an clean example of the exit() syscall used for exiting from a program. Many of you might be wondered to see why this being used is, the reason is the newer kernel don’t allow anymore the code execution from the stack so we have to use some C library wrapper or libc (responsible for providing us the malloc function). Usage at darker site: We write shellcode because we want the target program to function in a manner other than what was intended by the designer. One way to manipulate the program is to force it to make a system call or syscall. System calls in Linux are accomplished via software interrupts and are called with the int 0x80 instruction. -
Shells and Shell Scripting
Shells and Shell scripting What is a Shell? • A shell is a command line interpreter that is the interface between the user and the OS. • A “program launcher” of sorts. • The shell: o analyzes each command o determines what actions are to be performed o performs the actions • Example: wc –l file1 > file2 Which shell? • sh – Bourne shell o Most common, other shells are a superset o Good for programming • csh or tcsh – default for command line on CDF o C-like syntax o Best for interactive use. Not good for programming. • bash – default on Linux (Bourne again shell) o Based on sh, with some csh features. • korn – written by David Korn o Based on sh – Some claim best for programming. o Commercial product. Common shell facilities Shell startup When a shell is invoked, it does the following: 1. Read a special startup file (usually in home directory) 2. display prompt and wait for command 3. Ctrl-D on its own line terminates shell, otherwise, goto step 2. Shell startup files used to set shell options, set up environment variables, alias sh – executes .profile if it’s there. ksh – executes .profile if in interactive mode. Executes $ENV (usually $HOME/.kshrc) csh – executes .cshrc if it exists. If a login shell, executes .login bash – executes .bashrc, if a login shell, executes .bash_profile instead Executables vs. built-in commands Most commands you run are other compiled programs. Found in /bin Example: ls – shell locates ls binary in /bin directory and launches it Some are not compiled programs, but built into the shell: cd, echo Input-output redirection prog < infile > outfile ls > outfile 2>&1 # sh stdout and stderr Pipelining commands send the output from one command to the input of the next: ls -l | wc ps –aux | grep reid | sort Before a program is executed, the shell recognizes the special characters such as <, >, |, and rewires the standard input, output, or error file descriptors of the program about to be executed to point to the right files (or the standard input of another program). -
NETSTAT Command
NETSTAT Command | NETSTAT Command | Use the NETSTAT command to display network status of the local host. | | ┌┐────────────── | 55──NETSTAT─────6─┤ Option ├─┴──┬────────────────────────────────── ┬ ─ ─ ─ ────────────────────────────────────────5% | │┌┐───────────────────── │ | └─(──SELect───6─┤ Select_String ├─┴ ─ ┘ | Option: | ┌┐─COnn────── (1, 2) ──────────────── | ├──┼─────────────────────────── ┼ ─ ──────────────────────────────────────────────────────────────────────────────┤ | ├─ALL───(2)──────────────────── ┤ | ├─ALLConn─────(1, 2) ────────────── ┤ | ├─ARp ipaddress───────────── ┤ | ├─CLients─────────────────── ┤ | ├─DEvlinks────────────────── ┤ | ├─Gate───(3)─────────────────── ┤ | ├─┬─Help─ ┬─ ───────────────── ┤ | │└┘─?──── │ | ├─HOme────────────────────── ┤ | │┌┐─2ð────── │ | ├─Interval─────(1, 2) ─┼───────── ┼─ ┤ | │└┘─seconds─ │ | ├─LEVel───────────────────── ┤ | ├─POOLsize────────────────── ┤ | ├─SOCKets─────────────────── ┤ | ├─TCp serverid───(1) ─────────── ┤ | ├─TELnet───(4)───────────────── ┤ | ├─Up──────────────────────── ┤ | └┘─┤ Command ├───(5)──────────── | Command: | ├──┬─CP cp_command───(6) ─ ┬ ────────────────────────────────────────────────────────────────────────────────────────┤ | ├─DELarp ipaddress─ ┤ | ├─DRop conn_num──── ┤ | └─RESETPool──────── ┘ | Select_String: | ├─ ─┬─ipaddress────(3) ┬ ─ ───────────────────────────────────────────────────────────────────────────────────────────┤ | ├─ldev_num─────(4) ┤ | └─userid────(2) ─── ┘ | Notes: | 1 Only ALLCON, CONN and TCP are valid with INTERVAL. | 2 The userid -
The Linux Command Line Presentation to Linux Users of Victoria
The Linux Command Line Presentation to Linux Users of Victoria Beginners Workshop August 18, 2012 http://levlafayette.com What Is The Command Line? 1.1 A text-based user interface that provides an environment to access the shell, which interfaces with the kernel, which is the lowest abstraction layer to system resources (e.g., processors, i/o). Examples would include CP/M, MS-DOS, various UNIX command line interfaces. 1.2 Linux is the kernel; GNU is a typical suite of commands, utilities, and applications. The Linux kernel may be accessed by many different shells e.g., the original UNIX shell (sh), the TENEX C shell (tcsh), Korn shell (ksh), and explored in this presentation, the Bourne-Again Shell (bash). 1.3 The command line interface can be contrasted with the graphic user interface (GUI). A GUI interface typically consists of window, icon, menu, pointing-device (WIMP) suite, which is popular among casual users. Examples include MS-Windows, or the X- Window system. 1.4 A critical difference worth noting is that in UNIX-derived systems (such as Linux and Mac OS), the GUI interface is an application launched from the command-line interface, whereas with operating systems like contemporary versions of MS-Windows, the GUI is core and the command prompt is a native MS-Windows application. Why Use The Command Line? 2.1 The command line uses significantly less resources to carry out the same task; it requires less processor power, less memory, less hard-disk etc. Thus, it is preferred on systems where performance is considered critical e.g., supercomputers and embedded systems. -
APPENDIX a Aegis and Unix Commands
APPENDIX A Aegis and Unix Commands FUNCTION AEGIS BSD4.2 SYSS ACCESS CONTROL AND SECURITY change file protection modes edacl chmod chmod change group edacl chgrp chgrp change owner edacl chown chown change password chpass passwd passwd print user + group ids pst, lusr groups id +names set file-creation mode mask edacl, umask umask umask show current permissions acl -all Is -I Is -I DIRECTORY CONTROL create a directory crd mkdir mkdir compare two directories cmt diff dircmp delete a directory (empty) dlt rmdir rmdir delete a directory (not empty) dlt rm -r rm -r list contents of a directory ld Is -I Is -I move up one directory wd \ cd .. cd .. or wd .. move up two directories wd \\ cd . ./ .. cd . ./ .. print working directory wd pwd pwd set to network root wd II cd II cd II set working directory wd cd cd set working directory home wd- cd cd show naming directory nd printenv echo $HOME $HOME FILE CONTROL change format of text file chpat newform compare two files emf cmp cmp concatenate a file catf cat cat copy a file cpf cp cp Using and Administering an Apollo Network 265 copy std input to std output tee tee tee + files create a (symbolic) link crl In -s In -s delete a file dlf rm rm maintain an archive a ref ar ar move a file mvf mv mv dump a file dmpf od od print checksum and block- salvol -a sum sum -count of file rename a file chn mv mv search a file for a pattern fpat grep grep search or reject lines cmsrf comm comm common to 2 sorted files translate characters tic tr tr SHELL SCRIPT TOOLS condition evaluation tools existf test test