What is text processing in linux

How To Do Text Processing In Linux

In this article I will explain the text processing in Linux operating system. Linux is completely based on text files. So it is necessary to do text processing. In text processing we will do many tasks like application, slicing and dicing, comparing and editing.

Introduction

All Unix like operating system rely heavily on text files for several type of data storage. Text processing means manipulating the text. There are many programs used for text processing are as follows
1. cat— Concatenate files and print on the standard output
2. sort— Sort lines of text files
3. uniq— Omit repeated lines
4. cut— Remove sections from each line of files
5. paste— Merge lines of files
6. join— Join lines of two files on common field
7. comm— Compare two sorted files line by line
8. diff— Compare files line by line
9. patch— Apply a diff file to an original
10. tr— Translate characters
11. sed— Stream editor for filtering and transforming text
12. aspell— Interactive spell checker

Applications of text

Documents
We uses plain text formats for writing documents. It is easy to see how a small text file could be useful for keeping simple notes, it is also possible to write large documents in text format. To write a large document in a text format we use markup language. Unix based text processing systems were among the first systems that supported the advanced typographical layout needed by writers in technical disciplines.

Web pages
The world’s most popular type of electronic document is probably the web page. Web pages are text documents that use either hypertext markup language or extensible markup language as markup language to describe the documents visual format.

Email
Email is an intrinsically text based medium. Even non text attachments are converted into a text representation for transmission. We can see this for ourselves by downloading an email message and then viewing it in less. We will see that the message begins with a header that describes the source of the message and the processing it received during its journey, followed by the body of the message with its content.

Printer output
On Unix like system output destined for a printer is sent as plain text or if the page contains graphics then it converted into a text format page description language known as post script, which is then sent to a program that generates the graphics dots to be printed.

Program source code
Many of the command line programs found on Unix like systems were created to support system administration and software development and text processing. The reason text processing is important to software developers is that all software starts out as text. Source code the part of the program the programmer actually writes is always in text format.

cat
Cat program is used to visualize text content. There are many options in using cat program. One example is the –a option , which is used to display non-printing characters in the text. To create a test file using cat as a primitive word processor. To do this we will just enter the cat command and type our text followed by enter to properly end the line.

sort
The sort program sorts the contents of standard input or one or more files specified on the command line and sends the results to the standard output. Sort can accept multiple files on the command line as arguments, it is possible to merge multiple files into a single sorted file.

uniq
uniq performs a trivial task. When given a sorted file it removes any duplicate lines and sends the results to standard output. It is often used in conjunction with sort to clean the output of duplicates. Uniq only removes duplicate lines which are adjacent to each other.

Slicing and dicing

We will use three programs for slicing and dicing.
cut
The cut program is used to extract a section of text file from a line and output the extracted section to standard output. It can accept multiple arguments or input from standard input.

paste
The paste command does the opposite of cut. Rather than extracting a column of text from file, it adds on or more column of texts to a file. It does this by reading multiple files and combining the fields found in each file into a single stream on standard output.

join
join is like paste in that it adds columns to a file but it uses a unique way to do it. A join is an operation usually associated with relational databases where data from multiple tables with a shared key field is combined to form a desired result.

Comparing text

It is useful to compare versions of text files. For system administrators and software developers this is very important. A system administrator may need to compare a configuration file with a previous version of file to diagnose a problem in the system. We can use the following programs for comparing text.

comm
The comm program compares two text files and displays the lines that are unique to each one and the lines they have in common. To compare the two files using comm we use following command syntax
comm file1.txt file2.txt

diff
Like the comm program diff is used to detect the differences between files. However diff is more complex tool, supporting many output formats and the ability to process large collections of text files at once. diff is often used by software developers to examine changes between different version of the source code and thus has the ability to recursively examine directories of source code.

patch
The patch program is used to apply changes to text files. It accepts output from diff and is generally used to convert older version of files into newer version. patch will works on any text files not only source code.

Editing

We can done editing by using text editors in very interactive way means that we manually move our cursor around then type our changes. There are non interactive ways to edit text as well. We can use following program for non interactive editing.
tr
We will use the tr command to translate the characters or we can say that we will use tr command to convert the lowercase letter into uppercase letter and vice versa.

sed
The name sed is short for stream editor. It performs text editing on a stream of text either a set of specified files or standard input. sed is a powerful and complex program.

Источник

What is text processing tools?

What Is Text Processing? Using natural language processing (NLP) and machine learning, subfields of artificial intelligence, text processing tools are able to automatically understand human language and extract value from text data.

What are different text processing tools in Linux?

With that said, below are some of the useful file or text filters in Linux.

• Awk Command. Awk is a remarkable pattern scanning and processing language, it can be used to build useful filters in Linux.
• Sed Command.
• Grep, Egrep, Fgrep, Rgrep Commands.
• head Command.
• tail Command.
• sort Command.
• uniq Command.
• fmt Command.

What is text processing command?

This command sorts a text stream or file forwards or backwards, or according to various keys or character positions. Using the -m option, it merges presorted input files.

What are text processing utilities in Unix?

Overview of Unix Filters Text Processing Utilities: Filters are commands that read input from stdin and write output to stdout. By default, when using a shell terminal, the stdin is from the keyboard, and the stdout is to the terminal. Mechanisms to change the stdin and stdout will be covered in the next tutorials.

What do you mean by text formatting?

Formatted text is text that is displayed in a special, specified style. Text formatting data may be qualitative (e.g., font family), or quantitative (e.g., font size, or color). It may also indicate a style of emphasis (e.g., boldface, or italics), or a style of notation (e.g., strikethrough, or superscript).

Is formatting of text an example of text processing?

Answer: Word deals with formatting on three levels encompassing small and specific on up to big and broad—through characters, paragraphs, and sections. You apply different types of formatting to each of these parts. Character formatting includes selecting a font, a font size, bold or italics, and so on.

What is difference between $Cat ABC and $Cat ABC more?

cat command will dump the entire content of a file on the screen whereas more command will display content that would fit your screen and you can press enter to see rest of the content line by line.

What is the use of TR command in Linux?

The tr command in UNIX is a command line utility for translating or deleting characters. It supports a range of transformations including uppercase to lowercase, squeezing repeating characters, deleting specific characters and basic find and replace.

Which command tool should be used to rearrange the data in a line of text?

Learn Unix Sort Command with Examples: The Unix sort command is a simple command that can be used to rearrange the contents of text files line by line. The command is a filter command that sorts the input text and prints the result to stdout. By default, sorting is done line by line, starting from the first character.

What are filter commands?

In UNIX/Linux, filters are the set of commands that take input from standard input stream i.e. stdin, perform some operations and write output to standard output stream i.e. stdout. The stdin and stdout can be managed as per preferences using redirection and pipes. Common filter commands are: grep, more, sort. 1.

What is the use of pipe symbol?

Pipe is used to combine two or more commands, and in this, the output of one command acts as input to another command, and this command’s output may act as input to the next command and so on.

What are filters in Linux?

Filters are programs that take plain text(either stored in a file or produced by another program) as standard input, transforms it into a meaningful format, and then returns it as standard output. Linux has a number of filters.

Источник

What are the text processing tools in Linux?

Grep, sed, and AWK are all standard Linux tools that are able to process text. Each of these tools can read text files line-by-line and use regular expressions to perform operations on specific parts of the file.

What is text processing in Unix?

Text Processing in Unix Filters are commands that always read their input from ‘stdin’ and write their output to ‘stdout’. Users can use file redirection and ‘pipes’ to setup ‘stdin’ and ‘stdout’ as per their need.

Which is text processing command?

Text Processing Commands. Commands affecting text and text files sort. File sort utility, often used as a filter in a pipe. This command sorts a text stream or file forwards or backwards, or according to various keys or character positions.

What are Unix command line tools?

• awk.
• chmod.
• compress, uncompress.
• date.
• diff.
• grep.
• gzip, gunzip, zcat.
• head, tail.

What are text processing tools?

Text Processing Methods and Tools

• Word Frequency. This statistical method pinpoints the most frequently used words or expressions in a specific piece of text.
• Collocation.
• Concordance.
• TF-IDF.
• Topic Analysis.
• Sentiment Analysis.
• Intent Detection.
• Language Classification.

What is text processing give two command for text processing in Linux?

How do you create a process in Unix?

A new process can be created by the fork() system call. The new process consists of a copy of the address space of the original process. fork() creates new process from existing process. Existing process is called the parent process and the process is created newly is called child process.

What are the filter commands in Unix?

Common Unix filter programs are: cat, cut, grep, head, sort, uniq, and tail. Programs like awk and sed can be used to build quite complex filters because they are fully programmable.

What is text processing give two commands for text processing in Linux?

There are two standard UNIX commands that are often used to generate some textual output: cat and echo . The cat command reads each of the files specified in its arguments and writes the content of the files to stdout. The echo command writes its arguments to stdout.

How do I run command-line tools?

1. Right-click a Command Prompt shortcut.
2. Click Run As Administrator. When you open the Command Prompt window as Administrator, an operating-system dialog appears that asks you if you want to continue. Click Continue to proceed.

What are different command-line tools?

Windows Command-line Tools

• On this page.
• PowerShell (shell)
• PSReadLine (console editing helpers)
• ConEmu (console host)
• Cmder.
• Chocolatey (package manager)
• Babun (Cygwin preconfigured)
• Further Reading.

What is an example of text processing?

The text processing of a regular expression is a virtual editing machine, having a primitive programming language that has named registers (identifiers), and named positions in the sequence of characters comprising the text. Using these, the “text processor” can, for example, mark a region of text, and then move it.

Источник