Linux File System and Linux Commands
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LS-09EN. OS Permissions. SUID/SGID/Sticky. Extended Attributes
Operating Systems LS-09. OS Permissions. SUID/SGID/Sticky. Extended Attributes. Operating System Concepts 1.1 ys©2019 Linux/UNIX Security Basics Agenda ! UID ! GID ! Superuser ! File Permissions ! Umask ! RUID/EUID, RGID/EGID ! SUID, SGID, Sticky bits ! File Extended Attributes ! Mount/umount ! Windows Permissions ! File Systems Restriction Operating System Concepts 1.2 ys©2019 Domain Implementation in Linux/UNIX ! Two types domain (subjects) groups ! User Domains = User ID (UID>0) or User Group ID (GID>0) ! Superuser Domains = Root ID (UID=0) or Root Group ID (root can do everything, GID=0) ! Domain switch accomplished via file system. ! Each file has associated with it a domain bit (SetUID bit = SUID bit). ! When file is executed and SUID=on, then Effective UID is set to Owner of the file being executed. When execution completes Efective UID is reset to Real UID. ! Each subject (process) and object (file, socket,etc) has a 16-bit UID. ! Each object also has a 16-bit GID and each subject has one or more GIDs. ! Objects have access control lists that specify read, write, and execute permissions for user, group, and world. Operating System Concepts 1.3 ys©2019 Subjects and Objects Subjects = processes Objects = files (regular, directory, (Effective UID, EGID) devices /dev, ram /proc) RUID (EUID) Owner permissions (UID) RGID-main (EGID) Group Owner permissions (GID) +RGID-list Others RUID, RGID Others ID permissions Operating System Concepts 1.4 ys©2019 The Superuser (root) • Almost every Unix system comes with a special user in the /etc/passwd file with a UID=0. This user is known as the superuser and is normally given the username root. -
Ocaml Standard Library Ocaml V
OCaml Standard Library OCaml v. 3.12.0 | June 7, 2011 | Copyright c 2011 OCamlPro SAS | http://www.ocamlpro.com/ Standard Modules module List module Array Basic Data Types let len = List.length l let t = Array.create len v let t = Array.init len (fun pos -> v_at_pos) Pervasives All basic functions List.iter (fun ele -> ... ) l; let v = t.(pos) String Functions on Strings let l' = List.map(fun ele -> ... ) l t.(pos) <- v; Array Functions on Polymorphic Arrays let l' = List.rev l1 let len = Array.length t List Functions on Polymorphic Lists let acc' = List.fold left (fun acc ele -> ...) acc l let t' = Array.sub t pos len Char Functions on Characters let acc' = List.fold right (fun ele acc -> ...) l acc let t = Array.of_list list Int32 Functions on 32 bits Integers if List.mem ele l then ... let list = Array.to_list t Int64 Functions on 64 bits Integers if List.for all (fun ele -> ele >= 0) l then ... Array.iter (fun v -> ... ) t; Nativeint Functions on Native Integers if List.exists (fun ele -> ele < 0) l then ... let neg = List.find (fun x -> x < 0) ints Array.iteri (fun pos v -> ... ) t; Advanced Data Types let negs = List.find all (fun x -> x < 0) ints let t' = Array.map (fun v -> ... ) t let t' = Array.mapi (fun pos v -> ... ) t Buffer Automatically resizable strings let (negs,pos) = List.partition (fun x -> x < 0) ints let ele = List.nth 2 list let concat = Array.append prefix suffix Complex Complex Numbers Array.sort compare t; Digest MD5 Checksums let head = List.hd list Hashtbl Polymorphic Hash Tables let tail = List.tl list let value = List.assoc key assocs Queue Polymorphic FIFO module Char Stack Polymorphic LIFO if List.mem assoc key assocs then .. -
Understanding MPLS OAM Capabilities to Troubleshoot MPLS Networks
Understanding MPLS OAM capabilities to troubleshoot MPLS Networks Mukhtiar A. Shaikh ([email protected]) Moiz Moizuddin ([email protected]) 1 Agenda • MPLS Overview • Existing Ping/Trace Capabilities • LSP Ping/Trace –Theory of Operation –MPLS Echo Packet –Configuration and Troubleshooting Using LSP Ping/Trace •LSP Ping •LSP Trace –AToM VCCV • Summary 222 MPLS OAM Overview • Converged network implies a wide range of applications and OAM needs • IP Based Tools A flexible set of tools LSP Ping / Traceroute End-End OAM Attachment VC OAM’s MPLS OAM Attachment VC OAM’s Ingress Egress LSP Created by LDP and/or RSVP-TE CE PE PE CE PWE3 or VPN Label 333 Agenda • MPLS Overview • Existing Ping/Trace Capabilities • LSP Ping/Trace –Theory of Operation –MPLS Echo Packet –Configuration and Troubleshooting Using LSP Ping/Trace •LSP Ping •LSP Trace –AToM VCCV • Summary 444 IP Ping • PING makes use of the Internet Control Message Protocol (ICMP) protocol • Ping message of 2 types type=8: ICMP echo request messages type=0: ICMP echo reply message • Optional data field is used to store the time at which the ICMP echo request message has been send • The Round Trip Time (RTT) 555 IP Traceroute • Traceroute makes use of the Internet Control Message Protocol (ICMP) protocol and TTL field on the IP header • Traceroute is sent in a UDP packet encapsulated on an IP packet • TTL-field of an IP datagram is processed by each hop in two possible ways If a hop holds IP-datagram for more than one second, it decrements the TTL-field of that IP datagram by the number -
UNIX Workshop Series: Quick-Start Objectives
Part I UNIX Workshop Series: Quick-Start Objectives Overview – Connecting with ssh Command Window Anatomy Command Structure Command Examples Getting Help Files and Directories Wildcards, Redirection and Pipe Create and edit files Overview Connecting with ssh Open a Terminal program Mac: Applications > Utilities > Terminal ssh –Y [email protected] Linux: In local shell ssh –Y [email protected] Windows: Start Xming and PuTTY Create a saved session for the remote host name centos.css.udel.edu using username Connecting with ssh First time you connect Unix Basics Multi-user Case-sensitive Bash shell, command-line Commands Command Window Anatomy Title bar Click in the title bar to bring the window to the front and make it active. Command Window Anatomy Login banner Appears as the first line of a login shell. Command Window Anatomy Prompts Appears at the beginning of a line and usually ends in $. Command Window Anatomy Command input Place to type commands, which may have options and/or arguments. Command Window Anatomy Command output Place for command response, which may be many lines long. Command Window Anatomy Input cursor Typed text will appear at the cursor location. Command Window Anatomy Scroll Bar Will appear as needed when there are more lines than fit in the window. Command Window Anatomy Resize Handle Use the mouse to change the window size from the default 80x24. Command Structure command [arguments] Commands are made up of the actual command and its arguments. command -options [arguments] The arguments are further broken down into the command options which are single letters prefixed by a “-” and other arguments that identify data for the command. -
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. -
Linux Filesystem Hierarchy Chapter 1
Linux Filesystem Hierarchy Chapter 1. Linux Filesystem Hierarchy 1.1. Foreward When migrating from another operating system such as Microsoft Windows to another; one thing that will profoundly affect the end user greatly will be the differences between the filesystems. What are filesystems? A filesystem is the methods and data structures that an operating system uses to keep track of files on a disk or partition; that is, the way the files are organized on the disk. The word is also used to refer to a partition or disk that is used to store the files or the type of the filesystem. Thus, one might say I have two filesystems meaning one has two partitions on which one stores files, or that one is using the extended filesystem, meaning the type of the filesystem. The difference between a disk or partition and the filesystem it contains is important. A few programs (including, reasonably enough, programs that create filesystems) operate directly on the raw sectors of a disk or partition; if there is an existing file system there it will be destroyed or seriously corrupted. Most programs operate on a filesystem, and therefore won't work on a partition that doesn't contain one (or that contains one of the wrong type). Before a partition or disk can be used as a filesystem, it needs to be initialized, and the bookkeeping data structures need to be written to the disk. This process is called making a filesystem. Most UNIX filesystem types have a similar general structure, although the exact details vary quite a bit. -
CIS 90 - Lesson 2
CIS 90 - Lesson 2 Lesson Module Status • Slides - draft • Properties - done • Flash cards - NA • First minute quiz - done • Web calendar summary - done • Web book pages - gillay done • Commands - done • Lab tested – done • Print latest class roster - na • Opus accounts created for students submitting Lab 1 - • CCC Confer room whiteboard – done • Check that headset is charged - done • Backup headset charged - done • Backup slides, CCC info, handouts on flash drive - done 1 CIS 90 - Lesson 2 [ ] Has the phone bridge been added? [ ] Is recording on? [ ] Does the phone bridge have the mike? [ ] Share slides, putty, VB, eko and Chrome [ ] Disable spelling on PowerPoint 2 CIS 90 - Lesson 2 Instructor: Rich Simms Dial-in: 888-450-4821 Passcode: 761867 Emanuel Tanner Merrick Quinton Christopher Zachary Bobby Craig Jeff Yu-Chen Greg L Tommy Eric Dan M Geoffrey Marisol Jason P David Josh ? ? ? ? Leobardo Gabriel Jesse Tajvia Daniel W Jason W Terry? James? Glenn? Aroshani? ? ? ? ? ? ? = need to add (with add code) to enroll in Ken? Luis? Arturo? Greg M? Ian? this course Email me ([email protected]) a relatively current photo of your face for 3 points extra credit CIS 90 - Lesson 2 First Minute Quiz Please close your books, notes, lesson materials, forum and answer these questions in the order shown: 1. What command shows the other users logged in to the computer? 2. What is the lowest level, inner-most component of a UNIX/Linux Operating System called? 3. What part of UNIX/Linux is both a user interface and a programming language? email answers to: [email protected] 4 CIS 90 - Lesson 2 Commands Objectives Agenda • Understand how the UNIX login • Quiz operation works. -
Process Text Streams Using Filters
Process Text Streams Using Filters OBJECTIVE: Candidates should should be able to apply filters to text streams. 1 Process Text Streams Using Filters KeyKEY knowledge KNOWLEDGE area(s): AREAS: Send text files and output streams through text utility filters to modify the output using standard UNIX commands found in the GNU textutils package. 2 Process Text Streams Using Filters KEY FILES,TERMS, UTILITIES cat nl tail cut paste tr expand pr unexpand fmt sed uniq head sort wc hexdump split join tac 3 cat cat the editor - used as a rudimentary text editor. cat > short-message we are curious to meet penguins in Prague Crtl+D *Ctrl+D - command is used for ending interactive input. 4 cat cat the reader More commonly used to flush text to stdout. Options: -n number each line of output -b number only non-blank output lines -A show carriage return Example cat /etc/resolv.conf ▶ search mydomain.org nameserver 127.0.0.1 5 tac tac reads back-to-front This command is the same as cat except that the text is read from the last line to the first. tac short-message ▶ penguins in Prague to meet we are curious 6 head or tail using head or tail - often used to analyze logfiles. - by default, output 10 lines of text. List 20 first lines of /var/log/messages: head -n 20 /var/log/messages head -20 /var/log/messages List 20 last lines of /etc/aliases: tail -20 /etc/aliases 7 head or tail The tail utility has an added option that allows one to list the end of a text starting at a given line. -
Unix Command Line; Editors
Unix command line; editors Karl Broman Biostatistics & Medical Informatics, UW–Madison kbroman.org github.com/kbroman @kwbroman Course web: kbroman.org/AdvData My goal in this lecture is to convince you that (a) command-line-based tools are the things to focus on, (b) you need to choose a powerful, universal text editor (you’ll use it a lot), (c) you want to be comfortable and skilled with each. For your work to be reproducible, it needs to be code-based; don’t touch that mouse! Windows vs. Mac OSX vs. Linux Remote vs. Not 2 The Windows operating system is not very programmer-friendly. Mac OSX isn’t either, but under the hood, it’s just unix. Don’t touch the mouse! Open a terminal window and start typing. I do most of my work directly on my desktop or laptop. You might prefer to work remotely on a server, instead. But I can’t stand having any lag in looking at graphics. If you use Windows... Consider Git Bash (or Cygwin) or turn on the Windows subsystem for linux 3 Cygwin is an effort to get Unix command-line tools in Windows. Git Bash combines git (for version control) and bash (the unix shell); it’s simpler to deal with than Cygwin. Linux is now accessible in Windows 10, but you have to enable it. If you use a Mac... Consider Homebrew and iTerm2 Also the XCode command line tools 4 Homebrew is a packaging system; iTerm2 is a Terminal replacement. The XCode command line tools are a must for most unixy things on a Mac. -
File Formats
man pages section 4: File Formats Sun Microsystems, Inc. 4150 Network Circle Santa Clara, CA 95054 U.S.A. Part No: 817–3945–10 September 2004 Copyright 2004 Sun Microsystems, Inc. 4150 Network Circle, Santa Clara, CA 95054 U.S.A. All rights reserved. This product or document is protected by copyright and distributed under licenses restricting its use, copying, distribution, and decompilation. No part of this product or document may be reproduced in any form by any means without prior written authorization of Sun and its licensors, if any. Third-party software, including font technology, is copyrighted and licensed from Sun suppliers. Parts of the product may be derived from Berkeley BSD systems, licensed from the University of California. UNIX is a registered trademark in the U.S. and other countries, exclusively licensed through X/Open Company, Ltd. Sun, Sun Microsystems, the Sun logo, docs.sun.com, AnswerBook, AnswerBook2, and Solaris are trademarks or registered trademarks of Sun Microsystems, Inc. in the U.S. and other countries. All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International, Inc. in the U.S. and other countries. Products bearing SPARC trademarks are based upon an architecture developed by Sun Microsystems, Inc. The OPEN LOOK and Sun™ Graphical User Interface was developed by Sun Microsystems, Inc. for its users and licensees. Sun acknowledges the pioneering efforts of Xerox in researching and developing the concept of visual or graphical user interfaces for the computer industry. Sun holds a non-exclusive license from Xerox to the Xerox Graphical User Interface, which license also covers Sun’s licensees who implement OPEN LOOK GUIs and otherwise comply with Sun’s written license agreements. -
A Brief Introduction to Unix-2019-AMS
Brief Intro to Linux/Unix Brief Intro to Unix (contd) A Brief Introduction to o Brief History of Unix o Compilers, Email, Text processing o Basics of a Unix session o Image Processing Linux/Unix – AMS 2019 o The Unix File System Pete Pokrandt o Working with Files and Directories o The vi editor UW-Madison AOS Systems Administrator o Your Environment [email protected] o Common Commands Twitter @PTH1 History of Unix History of Unix History of Unix o Created in 1969 by Kenneth Thompson and Dennis o Today – two main variants, but blended o It’s been around for a long time Ritchie at AT&T o Revised in-house until first public release 1977 o System V (Sun Solaris, SGI, Dec OSF1, AIX, o It was written by computer programmers for o 1977 – UC-Berkeley – Berkeley Software Distribution (BSD) linux) computer programmers o 1983 – Sun Workstations produced a Unix Workstation o BSD (Old SunOS, linux, Mac OSX/MacOS) o Case sensitive, mostly lowercase o AT&T unix -> System V abbreviations 1 Basics of a Unix Login Session Basics of a Unix Login Session Basics of a Unix Login Session o The Shell – the command line interface, o Features provided by the shell o Logging in to a unix session where you enter commands, etc n Create an environment that meets your needs n login: username n Some common shells n Write shell scripts (batch files) n password: tImpAw$ n Define command aliases (this Is my password At work $) Bourne Shell (sh) OR n Manipulate command history IHateHaving2changeMypasswordevery3weeks!!! C Shell (csh) n Automatically complete the command -
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.