Awk — a Pattern Scanning and Processing Language (Second
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At—At, Batch—Execute Commands at a Later Time
at—at, batch—execute commands at a later time at [–csm] [–f script] [–qqueue] time [date] [+ increment] at –l [ job...] at –r job... batch at and batch read commands from standard input to be executed at a later time. at allows you to specify when the commands should be executed, while jobs queued with batch will execute when system load level permits. Executes commands read from stdin or a file at some later time. Unless redirected, the output is mailed to the user. Example A.1 1 at 6:30am Dec 12 < program 2 at noon tomorrow < program 3 at 1945 pm August 9 < program 4 at now + 3 hours < program 5 at 8:30am Jan 4 < program 6 at -r 83883555320.a EXPLANATION 1. At 6:30 in the morning on December 12th, start the job. 2. At noon tomorrow start the job. 3. At 7:45 in the evening on August 9th, start the job. 4. In three hours start the job. 5. At 8:30 in the morning of January 4th, start the job. 6. Removes previously scheduled job 83883555320.a. awk—pattern scanning and processing language awk [ –fprogram–file ] [ –Fc ] [ prog ] [ parameters ] [ filename...] awk scans each input filename for lines that match any of a set of patterns specified in prog. Example A.2 1 awk '{print $1, $2}' file 2 awk '/John/{print $3, $4}' file 3 awk -F: '{print $3}' /etc/passwd 4 date | awk '{print $6}' EXPLANATION 1. Prints the first two fields of file where fields are separated by whitespace. 2. Prints fields 3 and 4 if the pattern John is found. -
Wait, I Don't Want to Be the Linux Administrator for SAS VA
SESUG Paper 88-2017 Wait, I don’t want to be the Linux Administrator for SAS VA Jonathan Boase; Zencos Consulting ABSTRACT Whether you are a new SAS administrator or switching to a Linux environment, you have a complex mission. This job becomes even more formidable when you are working with a system like SAS Visual Analytics that requires multiple users loading data daily. Eventually a user will have data issues or create a disruption that causes the system to malfunction. When that happens, what do you do next? In this paper, we will go through the basics of a SAS Visual Analytics Linux environment and how to troubleshoot the system when issues arise. INTRODUCTION Many companies choose to implement SAS Visual Analytics in a Linux environment. With a distributed deployment, it’s the only choice but many chose this operating system because it reduces operating costs. If you are the newly chosen SAS platform administrator, you might be more versed in a Windows environment and feel intimidated by Linux. This paper introduces using basic Linux commands and methods for troubleshooting a SAS Visual Analytics environment. The paper assumes that SAS Visual Analytics is installed on a SAS 9.4 platform for Linux and that the reader has some familiarity with other operating systems, such as Windows. PLATFORM ADMINISTRATION 101 SAS platform administrators work with three main product areas. Each area provides a different functionality based on the task the administrator needs to perform. The following figure defines each area and provides a general overview of its purpose. Figure 1 Platform Administrator Tools Operating System SAS Management SAS Environment •Contains installed Console Manager software •Access and manage the •Monitor the •Contains logs used for metadata environment troubleshooting •Control database •Configure custom alerts •Administer host system connections users •Manage user accounts •Manage the LASR server With any operating system, there is always a lot to learn. -
Drilling Network Stacks with Packetdrill
Drilling Network Stacks with packetdrill NEAL CARDWELL AND BARATH RAGHAVAN Neal Cardwell received an M.S. esting and troubleshooting network protocols and stacks can be in Computer Science from the painstaking. To ease this process, our team built packetdrill, a tool University of Washington, with that lets you write precise scripts to test entire network stacks, from research focused on TCP and T the system call layer down to the NIC hardware. packetdrill scripts use a Web performance. He joined familiar syntax and run in seconds, making them easy to use during develop- Google in 2002. Since then he has worked on networking software for google.com, the ment, debugging, and regression testing, and for learning and investigation. Googlebot web crawler, the network stack in Have you ever had the experience of staring at a long network trace, trying to figure out what the Linux kernel, and TCP performance and on earth went wrong? When a network protocol is not working right, how might you find the testing. [email protected] problem and fix it? Although tools like tcpdump allow us to peek under the hood, and tools like netperf help measure networks end-to-end, reproducing behavior is still hard, and know- Barath Raghavan received a ing when an issue has been fixed is even harder. Ph.D. in Computer Science from UC San Diego and a B.S. from These are the exact problems that our team used to encounter on a regular basis during UC Berkeley. He joined Google kernel network stack development. Here we describe packetdrill, which we built to enable in 2012 and was previously a scriptable network stack testing. -
Bash Crash Course + Bc + Sed + Awk∗
Bash Crash course + bc + sed + awk∗ Andrey Lukyanenko, CSE, Aalto University Fall, 2011 There are many Unix shell programs: bash, sh, csh, tcsh, ksh, etc. The comparison of those can be found on-line 1. We will primary focus on the capabilities of bash v.4 shell2. 1. Each bash script can be considered as a text file which starts with #!/bin/bash. It informs the editor or interpretor which tries to open the file, what to do with the file and how should it be treated. The special character set in the beginning #! is a magic number; check man magic and /usr/share/file/magic on existing magic numbers if interested. 2. Each script (assume you created “scriptname.sh file) can be invoked by command <dir>/scriptname.sh in console, where <dir> is absolute or relative path to the script directory, e.g., ./scriptname.sh for current directory. If it has #! as the first line it will be invoked by this command, otherwise it can be called by command bash <dir>/scriptname.sh. Notice: to call script as ./scriptname.sh it has to be executable, i.e., call command chmod 555 scriptname.sh before- hand. 3. Variable in bash can be treated as integers or strings, depending on their value. There are set of operations and rules available for them. For example: #!/bin/bash var1=123 # Assigns value 123 to var1 echo var1 # Prints ’var1’ to output echo $var1 # Prints ’123’ to output var2 =321 # Error (var2: command not found) var2= 321 # Error (321: command not found) var2=321 # Correct var3=$var2 # Assigns value 321 from var2 to var3 echo $var3 # Prints ’321’ to output -
Chapter # 9 LEX and YACC
Chapter # 9 LEX and YACC Dr. Shaukat Ali Department of Computer Science University of Peshawar Lex and Yacc Lex and yacc are a matched pair of tools. Lex breaks down files into sets of "tokens," roughly analogous to words. Yacc takes sets of tokens and assembles them into higher-level constructs, analogous to sentences. Lex's output is mostly designed to be fed into some kind of parser. Yacc is designed to work with the output of Lex. 2 Lex and Yacc Lex and yacc are tools for building programs. Their output is itself code – Which needs to be fed into a compiler – May be additional user code is added to use the code generated by lex and yacc 3 Lex : A lexical analyzer generator Lex is a program designed to generate scanners, also known as tokenizers, which recognize lexical patterns in text Lex is an acronym that stands for "lexical analyzer generator.“ The main purpose is to facilitate lexical analysis The processing of character sequences in source code to produce tokens for use as input to other programs such as parsers Another tool for lexical analyzer generation is Flex 4 Lex : A lexical analyzer generator lex.lex is an a input file written in a language which describes the generation of lexical analyzer. The lex compiler transforms lex.l to a C program known as lex.yy.c. lex.yy.c is compiled by the C compiler to a file called a.out. The output of C compiler is the working lexical analyzer which takes stream of input characters and produces a stream of tokens. -
Project1: Build a Small Scanner/Parser
Project1: Build A Small Scanner/Parser Introducing Lex, Yacc, and POET cs5363 1 Project1: Building A Scanner/Parser Parse a subset of the C language Support two types of atomic values: int float Support one type of compound values: arrays Support a basic set of language concepts Variable declarations (int, float, and array variables) Expressions (arithmetic and boolean operations) Statements (assignments, conditionals, and loops) You can choose a different but equivalent language Need to make your own test cases Options of implementation (links available at class web site) Manual in C/C++/Java (or whatever other lang.) Lex and Yacc (together with C/C++) POET: a scripting compiler writing language Or any other approach you choose --- must document how to download/use any tools involved cs5363 2 This is just starting… There will be two other sub-projects Type checking Check the types of expressions in the input program Optimization/analysis/translation Do something with the input code, output the result The starting project is important because it determines which language you can use for the other projects Lex+Yacc ===> can work only with C/C++ POET ==> work with POET Manual ==> stick to whatever language you pick This class: introduce Lex/Yacc/POET to you cs5363 3 Using Lex to build scanners lex.yy.c MyLex.l lex/flex lex.yy.c a.out gcc/cc Input stream a.out tokens Write a lex specification Save it in a file (MyLex.l) Compile the lex specification file by invoking lex/flex lex MyLex.l A lex.yy.c file is generated -
User Manual for Ox: an Attribute-Grammar Compiling System Based on Yacc, Lex, and C Kurt M
Computer Science Technical Reports Computer Science 12-1992 User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C Kurt M. Bischoff Iowa State University Follow this and additional works at: http://lib.dr.iastate.edu/cs_techreports Part of the Programming Languages and Compilers Commons Recommended Citation Bischoff, Kurt M., "User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C" (1992). Computer Science Technical Reports. 21. http://lib.dr.iastate.edu/cs_techreports/21 This Article is brought to you for free and open access by the Computer Science at Iowa State University Digital Repository. It has been accepted for inclusion in Computer Science Technical Reports by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. User Manual for Ox: An Attribute-Grammar Compiling System based on Yacc, Lex, and C Abstract Ox generalizes the function of Yacc in the way that attribute grammars generalize context-free grammars. Ordinary Yacc and Lex specifications may be augmented with definitions of synthesized and inherited attributes written in C syntax. From these specifications, Ox generates a program that builds and decorates attributed parse trees. Ox accepts a most general class of attribute grammars. The user may specify postdecoration traversals for easy ordering of side effects such as code generation. Ox handles the tedious and error-prone details of writing code for parse-tree management, so its use eases problems of security and maintainability associated with that aspect of translator development. The translators generated by Ox use internal memory management that is often much faster than the common technique of calling malloc once for each parse-tree node. -
UNIX X Command Tips and Tricks David B
SESUG Paper 122-2019 UNIX X Command Tips and Tricks David B. Horvath, MS, CCP ABSTRACT SAS® provides the ability to execute operating system level commands from within your SAS code – generically known as the “X Command”. This session explores the various commands, the advantages and disadvantages of each, and their alternatives. The focus is on UNIX/Linux but much of the same applies to Windows as well. Under SAS EG, any issued commands execute on the SAS engine, not necessarily on the PC. X %sysexec Call system Systask command Filename pipe &SYSRC Waitfor Alternatives will also be addressed – how to handle when NOXCMD is the default for your installation, saving results, and error checking. INTRODUCTION In this paper I will be covering some of the basics of the functionality within SAS that allows you to execute operating system commands from within your program. There are multiple ways you can do so – external to data steps, within data steps, and within macros. All of these, along with error checking, will be covered. RELEVANT OPTIONS Execution of any of the SAS System command execution commands depends on one option's setting: XCMD Enables the X command in SAS. Which can only be set at startup: options xcmd; ____ 30 WARNING 30-12: SAS option XCMD is valid only at startup of the SAS System. The SAS option is ignored. Unfortunately, ff NOXCMD is set at startup time, you're out of luck. Sorry! You might want to have a conversation with your system administrators to determine why and if you can get it changed. -
Useful Commands in Linux and Other Tools for Quality Control
Useful commands in Linux and other tools for quality control Ignacio Aguilar INIA Uruguay 05-2018 Unix Basic Commands pwd show working directory ls list files in working directory ll as before but with more information mkdir d make a directory d cd d change to directory d Copy and moving commands To copy file cp /home/user/is . To copy file directory cp –r /home/folder . to move file aa into bb in folder test mv aa ./test/bb To delete rm yy delete the file yy rm –r xx delete the folder xx Redirections & pipe Redirection useful to read/write from file !! aa < bb program aa reads from file bb blupf90 < in aa > bb program aa write in file bb blupf90 < in > log Redirections & pipe “|” similar to redirection but instead to write to a file, passes content as input to other command tee copy standard input to standard output and save in a file echo copy stream to standard output Example: program blupf90 reads name of parameter file and writes output in terminal and in file log echo par.b90 | blupf90 | tee blup.log Other popular commands head file print first 10 lines list file page-by-page tail file print last 10 lines less file list file line-by-line or page-by-page wc –l file count lines grep text file find lines that contains text cat file1 fiel2 concatenate files sort sort file cut cuts specific columns join join lines of two files on specific columns paste paste lines of two file expand replace TAB with spaces uniq retain unique lines on a sorted file head / tail $ head pedigree.txt 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 8 0 0 9 0 0 10 -
The AWK Programming Language
The Programming ~" ·. Language PolyAWK- The Toolbox Language· Auru:o V. AHo BRIAN W.I<ERNIGHAN PETER J. WEINBERGER TheAWK4 Programming~ Language TheAWI(. Programming~ Language ALFRED V. AHo BRIAN w. KERNIGHAN PETER J. WEINBERGER AT& T Bell Laboratories Murray Hill, New Jersey A ADDISON-WESLEY•• PUBLISHING COMPANY Reading, Massachusetts • Menlo Park, California • New York Don Mills, Ontario • Wokingham, England • Amsterdam • Bonn Sydney • Singapore • Tokyo • Madrid • Bogota Santiago • San Juan This book is in the Addison-Wesley Series in Computer Science Michael A. Harrison Consulting Editor Library of Congress Cataloging-in-Publication Data Aho, Alfred V. The AWK programming language. Includes index. I. AWK (Computer program language) I. Kernighan, Brian W. II. Weinberger, Peter J. III. Title. QA76.73.A95A35 1988 005.13'3 87-17566 ISBN 0-201-07981-X This book was typeset in Times Roman and Courier by the authors, using an Autologic APS-5 phototypesetter and a DEC VAX 8550 running the 9th Edition of the UNIX~ operating system. -~- ATs.T Copyright c 1988 by Bell Telephone Laboratories, Incorporated. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopy ing, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America. Published simultaneously in Canada. UNIX is a registered trademark of AT&T. DEFGHIJ-AL-898 PREFACE Computer users spend a lot of time doing simple, mechanical data manipula tion - changing the format of data, checking its validity, finding items with some property, adding up numbers, printing reports, and the like. -
Yacc a Tool for Syntactic Analysis
1 Yacc a tool for Syntactic Analysis CS 315 – Programming Languages Pinar Duygulu Bilkent University CS315 Programming Languages © Pinar Duygulu Lex and Yacc 2 1) Lexical Analysis: Lexical analyzer: scans the input stream and converts sequences of characters into tokens. Lex is a tool for writing lexical analyzers. 2) Syntactic Analysis (Parsing): Parser: reads tokens and assembles them into language constructs using the grammar rules of the language. Yacc is a tool for constructing parsers. Yet Another Compiler to Compiler Reads a specification file that codifies the grammar of a language and generates a parsing routine CS315 Programming Languages © Pinar Duygulu 3 Yacc • Yacc specification describes a Context Free Grammar (CFG), that can be used to generate a parser. Elements of a CFG: 1. Terminals: tokens and literal characters, 2. Variables (nonterminals): syntactical elements, 3. Production rules, and 4. Start rule. CS315 Programming Languages © Pinar Duygulu 4 Yacc Format of a production rule: symbol: definition {action} ; Example: A → Bc is written in yacc as a: b 'c'; CS315 Programming Languages © Pinar Duygulu 5 Yacc Format of a yacc specification file: declarations %% grammar rules and associated actions %% C programs CS315 Programming Languages © Pinar Duygulu 6 Declarations To define tokens and their characteristics %token: declare names of tokens %left: define left-associative operators %right: define right-associative operators %nonassoc: define operators that may not associate with themselves %type: declare the type of variables %union: declare multiple data types for semantic values %start: declare the start symbol (default is the first variable in rules) %prec: assign precedence to a rule %{ C declarations directly copied to the resulting C program %} (E.g., variables, types, macros…) CS315 Programming Languages © Pinar Duygulu 7 A simple yacc specification to accept L={ anbn | n>1}. -
Binpac: a Yacc for Writing Application Protocol Parsers
binpac: A yacc for Writing Application Protocol Parsers Ruoming Pang∗ Vern Paxson Google, Inc. International Computer Science Institute and New York, NY, USA Lawrence Berkeley National Laboratory [email protected] Berkeley, CA, USA [email protected] Robin Sommer Larry Peterson International Computer Science Institute Princeton University Berkeley, CA, USA Princeton, NJ, USA [email protected] [email protected] ABSTRACT Similarly, studies of Email traffic [21, 46], peer-to-peer applica- A key step in the semantic analysis of network traffic is to parse the tions [37], online gaming, and Internet attacks [29] require under- traffic stream according to the high-level protocols it contains. This standing application-level traffic semantics. However, it is tedious, process transforms raw bytes into structured, typed, and semanti- error-prone, and sometimes prohibitively time-consuming to build cally meaningful data fields that provide a high-level representation application-level analysis tools from scratch, due to the complexity of the traffic. However, constructing protocol parsers by hand is a of dealing with low-level traffic data. tedious and error-prone affair due to the complexity and sheer num- We can significantly simplify the process if we can leverage a ber of application protocols. common platform for various kinds of application-level traffic anal- This paper presents binpac, a declarative language and com- ysis. A key element of such a platform is application-protocol piler designed to simplify the task of constructing robust and effi- parsers that translate packet streams into high-level representations cient semantic analyzers for complex network protocols. We dis- of the traffic, on top of which we can then use measurement scripts cuss the design of the binpac language and a range of issues that manipulate semantically meaningful data elements such as in generating efficient parsers from high-level specifications.