File Ownership and Access Permissions on Linux
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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. -
Software Distributor Administration Guide for HP-UX 11I
Software Distributor Administration Guide for HP-UX 11i HP Computers Manufacturing Part Number: B2355-90754 June 2002, Edition 3 © Copyright 2002 Hewlett-Packard Company. Legal Notices The information in this document is subject to change without notice. Hewlett-Packard makes no warranty of any kind with regard to this manual, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Hewlett-Packard shall not be held liable for errors contained herein or direct, indirect, special, incidental or consequential damages in connection with the furnishing, performance, or use of this material. Warranty A copy of the specific warranty terms applicable to your Hewlett-Packard product and replacement parts can be obtained from your local Sales and Service Office. Restricted Rights Legend Use, duplication or disclosure by the U.S. Government is subject to restrictions as set forth in subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013 for DOD agencies, and subparagraphs (c) (1) and (c) (2) of the Commercial Computer Software Restricted Rights clause at FAR 52.227-19 for other agencies. HEWLETT-PACKARD COMPANY 3000 Hanover Street Palo Alto, California 94304 U.S.A. Use of this document and any supporting software media supplied for this pack is restricted to this product only. Additional copies of the programs may be made for security and back-up purposes only. Resale of the programs, in their present form or with alterations, is expressly prohibited. Copyright Notice Copyright 1997-2002 Hewlett-Packard Company. All rights reserved. -
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 -
The Linux Command Line
The Linux Command Line Fifth Internet Edition William Shotts A LinuxCommand.org Book Copyright ©2008-2019, William E. Shotts, Jr. This work is licensed under the Creative Commons Attribution-Noncommercial-No De- rivative Works 3.0 United States License. To view a copy of this license, visit the link above or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042. A version of this book is also available in printed form, published by No Starch Press. Copies may be purchased wherever fine books are sold. No Starch Press also offers elec- tronic formats for popular e-readers. They can be reached at: https://www.nostarch.com. Linux® is the registered trademark of Linus Torvalds. All other trademarks belong to their respective owners. This book is part of the LinuxCommand.org project, a site for Linux education and advo- cacy devoted to helping users of legacy operating systems migrate into the future. You may contact the LinuxCommand.org project at http://linuxcommand.org. Release History Version Date Description 19.01A January 28, 2019 Fifth Internet Edition (Corrected TOC) 19.01 January 17, 2019 Fifth Internet Edition. 17.10 October 19, 2017 Fourth Internet Edition. 16.07 July 28, 2016 Third Internet Edition. 13.07 July 6, 2013 Second Internet Edition. 09.12 December 14, 2009 First Internet Edition. Table of Contents Introduction....................................................................................................xvi Why Use the Command Line?......................................................................................xvi -
File Permissions Do Not Restrict Root
Filesystem Security 1 General Principles • Files and folders are managed • A file handle provides an by the operating system opaque identifier for a • Applications, including shells, file/folder access files through an API • File operations • Access control entry (ACE) – Open file: returns file handle – Allow/deny a certain type of – Read/write/execute file access to a file/folder by – Close file: invalidates file user/group handle • Access control list (ACL) • Hierarchical file organization – Collection of ACEs for a – Tree (Windows) file/folder – DAG (Linux) 2 Discretionary Access Control (DAC) • Users can protect what they own – The owner may grant access to others – The owner may define the type of access (read/write/execute) given to others • DAC is the standard model used in operating systems • Mandatory Access Control (MAC) – Alternative model not covered in this lecture – Multiple levels of security for users and documents – Read down and write up principles 3 Closed vs. Open Policy Closed policy Open Policy – Also called “default secure” • Deny Tom read access to “foo” • Give Tom read access to “foo” • Deny Bob r/w access to “bar” • Give Bob r/w access to “bar • Tom: I would like to read “foo” • Tom: I would like to read “foo” – Access denied – Access allowed • Tom: I would like to read “bar” • Tom: I would like to read “bar” – Access allowed – Access denied 4 Closed Policy with Negative Authorizations and Deny Priority • Give Tom r/w access to “bar” • Deny Tom write access to “bar” • Tom: I would like to read “bar” – Access -
Student Number: Surname: Given Name
Computer Science 2211a Midterm Examination Sample Solutions 9 November 20XX 1 hour 40 minutes Student Number: Surname: Given name: Instructions/Notes: The examination has 35 questions on 9 pages, and a total of 110 marks. Put all answers on the question paper. This is a closed book exam. NO ELECTRONIC DEVICES OF ANY KIND ARE ALLOWED. 1. [4 marks] Which of the following Unix commands/utilities are filters? Correct answers are in blue. mkdir cd nl passwd grep cat chmod scriptfix mv 2. [1 mark] The Unix command echo HOME will print the contents of the environment variable whose name is HOME. True False 3. [1 mark] In C, the null character is another name for the null pointer. True False 4. [3 marks] The protection code for the file abc.dat is currently –rwxr--r-- . The command chmod a=x abc.dat is equivalent to the command: a. chmod 755 abc.dat b. chmod 711 abc.dat c. chmod 155 abc.dat d. chmod 111 abc.dat e. none of the above 5. [3 marks] The protection code for the file abc.dat is currently –rwxr--r-- . The command chmod ug+w abc.dat is equivalent to the command: a. chmod 766 abc.dat b. chmod 764 abc.dat c. chmod 754 abc.dat d. chmod 222 abc.dat e. none of the above 2 6. [3 marks] The protection code for def.dat is currently dr-xr--r-- , and the protection code for def.dat/ghi.dat is currently -r-xr--r-- . Give one or more chmod commands that will set the protections properly so that the owner of the two files will be able to delete ghi.dat using the command rm def.dat/ghi.dat chmod u+w def.dat or chmod –r u+w def.dat 7. -
Unix Security Overview: 1
CIS/CSE 643: Computer Security (Syracuse University) Unix Security Overview: 1 Unix Security Overview 1 User and Group • Users – root: super user (uid = 0) – daemon: handle networks. – nobody: owns no files, used as a default user for unprivileged operations. ∗ Web browser can run with this mode. – User needs to log in with a password. The encrypted password is stored in /etc/shadow. – User information is stored in /etc/passwd, the place that was used to store passwords (not anymore). The following is an example of an entry in this file. john:x:30000:40000:John Doe:/home/john:/usr/local/bin/tcsh • Groups – Sometimes, it is more convenient if we can assign permissions to a group of users, i.e. we would like to assign permission based on groups. – A user has a primary group (listed in /etc/passwd), and this is the one associated to the files the user created. – Any user can be a member of multiple groups. – Group member information is stored in /etc/group % groups uid (display the groups that uid belongs to) – For systems that use NIS (Network Information Service), originally called Yellow Page (YP), we can get the group information using the command ypcat. % ypcat group (can display all the groups and their members) 2 File Permissions • File Permissions – The meaning of the permission bits in Unix. ∗ Owner (u), Group (g), and Others (o). ∗ Readable (r), Writable (w), and Executable (x). ∗ Example: -rwxrwxrwx (777) • Permissions on Directories: – r: the directory can be listed. – w: can create/delete a file or a directory within the directory. -
File Security Lock Down Your Data
File Security Lock Down Your Data Brian Reames January 22, 2012 Table of Contents 1.0 Basic Linux Permissions...............................................................................................................4 1.1 Determining Permissions……………………………………………………………………..................... 5 1.2 File Permissions vs. Directory Permissions………………………………………………….............. 6 1.3 Changing Permissions………………………………………………………………………….................... 7 1.3.1 Symbolic Method…………………………………………………………………….................... 8 1.3.2 Octal Method………………………………………………………………………..................... 10 1.3.3 Changing Permissions Graphically……………………………………………….............. 12 1.4 Examples of Unintentional Access…………………………………………………………................. 13 2.0 Setting Default Permissions………………………………………………………………………...................... 15 2.1 Common umask Settings……………………………………………………………………....................17 3.0 Advanced Linux Permissions……………………………………………………………………….................... 18 3.1 Special Permission: setuid………………………………………………………………….....................19 3.1.1 Setting the setuid Permission……………………………………………………................ 20 3.1.2 Caution Regarding setuid………………………………………………………….................22 3.2 Special Permission setgid……………………………………………………………………................... 23 3.2.1 setgid on a File……………………………………………………………………...................... 24 3.2.2 setgid on a Directory……………………………………………………………….................. 25 3.2.3 Caution Regarding setgid…………………………………………………………................. 28 3.3 Special Permission: sticky bit……………………………………………………………….................. -
Pingdirectory Administration Guide Version
Release 7.3.0.3 Server Administration Guide PingDirectory | Contents | ii Contents PingDirectory™ Product Documentation................................................ 20 Overview of the Server............................................................................. 20 Server Features.................................................................................................................................20 Administration Framework.................................................................................................................21 Server Tools Location....................................................................................................................... 22 Preparing Your Environment....................................................................22 Before You Begin.............................................................................................................................. 22 System requirements..............................................................................................................22 Installing Java......................................................................................................................... 23 Preparing the Operating System (Linux).......................................................................................... 24 Configuring the File Descriptor Limits.................................................................................... 24 File System Tuning.................................................................................................................25 -
Install and Run External Command Line Softwares
job monitor and control top: similar to windows task manager (space to refresh, q to exit) w: who is there ps: all running processes, PID, status, type ps -ef | grep yyin bg: move current process to background fg: move current process to foreground jobs: list running and suspended processes kill: kill processes kill pid (could find out using top or ps) 1 sort, cut, uniq, join, paste, sed, grep, awk, wc, diff, comm, cat All types of bioinformatics sequence analyses are essentially text processing. Unix Shell has the above commands that are very useful for processing texts and also allows the output from one command to be passed to another command as input using pipe (“|”). less cosmicRaw.txt | cut -f2,3,4,5,8,13 | awk '$5==22' | cut -f1 | sort -u | wc This makes the processing of files using Shell very convenient and very powerful: you do not need to write output to intermediate files or load all data into the memory. For example, combining different Unix commands for text processing is like passing an item through a manufacturing pipeline when you only care about the final product 2 Hands on example 1: cosmic mutation data - Go to UCSC genome browser website: http://genome.ucsc.edu/ - On the left, find the Downloads link - Click on Human - Click on Annotation database - Ctrl+f and then search “cosmic” - On “cosmic.txt.gz” right-click -> copy link address - Go to the terminal and wget the above link (middle click or Shift+Insert to paste what you copied) - Similarly, download the “cosmicRaw.txt.gz” file - Under your home, create a folder -
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 -
Manipulating Files and Directories
MANIPULATING FILES AND DIRECTORIES At this point, we are ready for some real work! This chapter will introduce the following commands: z cp—Copy files and directories. z mv—Move/rename files and directories. z mkdir—Create directories. z rm—Remove files and directories. z ln—Create hard and symbolic links. These five commands are among the most frequently used Linux com- mands. They are used for manipulating both files and directories. Now, to be frank, some of the tasks performed by these commands are more easily done with a graphical file manager. With a file manager, we can drag and drop a file from one directory to another, cut and paste files, delete files, and so on. So why use these old command-line programs? www.it-ebooks.info The answer is power and flexibility. While it is easy to perform simple file manipulations with a graphical file manager, complicated tasks can be easier with the command-line programs. For example, how could we copy all the HTML files from one directory to another—but only those that do not exist in the destination directory or are newer than the versions in the destination directory? Pretty hard with a file manager. Pretty easy with the command line: cp -u *.html destination Wildcards Before we begin using our commands, we need to talk about the shell fea- ture that makes these commands so powerful. Because the shell uses file- names so much, it provides special characters to help you rapidly specify groups of filenames. These special characters are called wildcards.