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Get number from line bash

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This is a short post on how to recognize numbers such as simple integers, real numbers and special codes such as zip codes and credit card numbers and also extract these number from unstructured text in the popular bash Bourne Again Shell shell or scripting language. Bash is the default Unix console or terminal window on Macintosh computers as well as a number of other Apple products. It is also used by cygwin and several other variants of Unix and Linux. Regular expressions are a compact efficient way of representing patterns of characters including the letters in the English alphabet and digits.

SEE VIDEO BY TOPIC: Shell Scripting Tutorial-49: Count the number of words & sentences in a text file without using 'wc'

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SEE VIDEO BY TOPIC: Shell Script - Find Lines with Set Number of Words on Them - Linux - BASH tutorial

Regular Expressions for Numbers in BASH

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This is a short post on how to recognize numbers such as simple integers, real numbers and special codes such as zip codes and credit card numbers and also extract these number from unstructured text in the popular bash Bourne Again Shell shell or scripting language.

Bash is the default Unix console or terminal window on Macintosh computers as well as a number of other Apple products. It is also used by cygwin and several other variants of Unix and Linux. Regular expressions are a compact efficient way of representing patterns of characters including the letters in the English alphabet and digits. There is extensive information on the web on regular expression. Interested readers can start with the Wikipedia page on regular expressions.

The goal of this post in to illustrate specifically how to recognize common types of numbers using regular expressions in BASH. The regular expressions in the examples will also work in some other environments. NOTE: If you are new to programming or regular expressions, regular expressions are not derived from the English language or basic arithmetic taught in schools. Generally aspects of programming that are not close to English or standard mathematics are harder to master and require more practice, drilling, and subsequent continued use to master.

Regular expressions are way out there in the cryptic computer notation wilderness. The example bash scripts are listed below. They are also available at GitHub. This script recognizes various types of numbers including integers, real numbers, complex numbers, and special codes including zip codes, telephone numbers, and credit card numbers. This short script demonstrate how to use the regular expressions for numbers to extract numbers and numeric data from unstructured text, a common problem in this age of the Internet.

This is a script to run a series of tests on the isnumber. John F. McGowan, Ph. He has been a Visiting Scholar at HP Labs developing computer vision algorithms and software for mobile devices. He has worked as a contractor at NASA Ames Research Center involved in the research and development of image and video processing algorithms and technology.

He has published articles on the origin and evolution of life, the exploration of Mars anticipating the discovery of methane on Mars , and cheap access to space. He has a Ph. He can be reached at jmcgowan11 earthlink. Very long script. I wrote about Linux regex before. Regex reduces time and effort. Thanks for the article. Save my name, email, and website in this browser for the next time I comment.

Leave this field empty. Notify me of follow-up comments by email. Applied Math. Get more stuff like this Get interesting math updates directly in your inbox. Related Posts. About The Author John F. Mokhtar Ebrahim March 3, Leave a Reply Cancel reply Save my name, email, and website in this browser for the next time I comment. Join thousands of math enthusiasts Get free math updates directly in your inbox.

Keyboard Input and Arithmetic

A shell script is a text file with a list of shell commands and it is executed like a program to perform a task or a set of tasks. The primary aim of a shell script is to automate tasks and save time. It is important to understand basic structure of a shell script, since it is you interact with a computing clusters via shell scripts See next chapter on Sun Grid Engine. There are many different shells available in Unix systems.

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I am glad that you are here! I was working on bioinformatics a few years ago and was amazed by those single-word bash commands which are much faster than my dull scripts, time saved through learning command-line shortcuts and scripting. Recent years I am working on cloud computing and I keep recording those useful commands here. Not all of them is oneliner, but i put effort on making them brief and swift.

Shell Programming and Scripting

By using our site, you acknowledge that you have read and understand our Cookie Policy , Privacy Policy , and our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Your attempt with sed is almost right, just need a add a single whitespace character for excluding from replacement,. You can also use GNU grep with a -E regular expression syntax and -o for matching only words which include digits and dots. How to fish: Here is the fantastic regex featuring a wysiwyg regexp editor including a large knowledge base. With shell parameter expansion :. Learn more.

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Thanks for the question. Another way to do it is with head and tail. Your way might be easier. I want just to edit first line of file by appending something to the first line and rest is same.

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Number lines in a file

If you often create Bash scripts, you may sometimes need to get the length of a string or find out the length of a variable that stores some string. This short note shows how to find out the length of a string from the Linux command line and how to count the length of the each line in a file. You will also see how to get the length of a string if it is stored in a variable in Bash and then assign that calculated number of characters to another variable.

SEE VIDEO BY TOPIC: Shell Scripting Tutorial for Beginners 4 - Pass Arguments to a Bash-Script

Previous Contents Next. Up to now, our scripts have not been interactive. That is, they did not require any input from the user. In this lesson, we will see how your scripts can ask questions, and get and use responses. To get input from the keyboard, you use the read command.

Bash: String Length – How To Find Out

By using our site, you acknowledge that you have read and understand our Cookie Policy , Privacy Policy , and our Terms of Service. It only takes a minute to sign up. Trying to figure out how to convert an argument to an integer to perform arithmetic on, and then print it out, say for addOne. In bash, one does not "convert an argument to an integer to perform arithmetic". In bash, variables are treated as integer or string depending on context. For example:. You should be aware that bash as opposed to ksh93, zsh or yash only performs integer arithmetic. If you have floating point numbers numbers with decimals , then there are other tools to assist.

The useful -c option prefixes each line of the input file with its number of occurrences. 3 This line occurs three times. bash$ sort testfile | uniq -c | sort -nr 3 This line occurs three Using cut to extract message headers from an e-mail folder.

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