Guide to UNIX Using Linux 4th Ed

Pipe Operator

A symbol (|) used in UNIX/Linux commands to redirect the output of one command as input to another command.

Grep Command

A command used in UNIX/Linux to search for a specified pattern in a file and display the lines containing the pattern.

Uniq Command

A command used in UNIX/Linux to remove duplicate lines from a file.

Comm Command

A command used in UNIX/Linux to compare two files.

Diff Command

A command used in UNIX/Linux to compare and select the differences between two files.

Wc Command

A command used in UNIX/Linux to count words, characters, and lines in a file.

Sed Command

A command used in UNIX/Linux for stream editing.

Tr Command

A command used in UNIX/Linux to translate and delete characters.

Pr Command

A command used in UNIX/Linux to format and print text.

Awk Command

A command used in UNIX/Linux to invoke Awk, a processing and pattern-scanning language.

UNIX/Linux systems

Operating systems that offer a combination of grep-type commands like grep, egrep, fgrep, and zgrep.

grep

Command used to search for patterns in files.

egrep

Command used for "extended" or more complex expressions, also executed as grep -E.

fgrep

Command used to search for fixed or text strings only, also executed as grep -F on most systems.

zgrep

Command used to perform searches on compressed or zipped files.

uniq command

Command that removes duplicate lines from a file, requiring sorted input.

Syntax

The structure or format in which a command is written.

-u option

Outputs only the lines of the source file that are not duplicated.

-d option

Outputs one copy of each line that has a duplicate and does not show unique lines.

-i option

Ignores case sensitivity.

-c option

Starts each line by showing the number of each instance.

comm command

Command that identifies duplicate lines in two files without deleting them.

diff command

Command that shows lines that differ between two files.

wc command

Command used to count the number of lines, words, and bytes in text files.

Sed

A stream editor used for making global changes on one or more files, with options like deleting lines, printing lines, substituting text, and appending text.

Tr Command

A command that translates characters by copying data from standard input to standard output, substituting or deleting characters specified by options and patterns.

Pr Command

A command that prints specified files in paginated form on standard output, with options for customizing headers, double-spacing output, and setting the number of lines per page.

Logical Structures

Files consist of records, and records consist of fields, representing logical entities like a payroll file, an employee pay record, or a field for an employee Social Security number.

Record Design

The organization of information into files, records, and fields, influencing the efficiency and effectiveness of data handling commands like selection, manipulation, and transformation.

Shell scripts

Scripts used to automate tasks in an application and can be run using alternate methods.

Record layout

Identifies each field in a record by name and data type, such as numeric or nonnumeric, to store relevant information.

Programmer Activity Status Report

A report that summarizes the activities of programmers and projects.

Field separator

Character used to separate fields in a record, such as a colon (:).

Numeric field

A field in a record that contains numerical data, preferred for uniquely identifying records due to faster interpretation by computers.

Project status codes

Numeric codes (1=Unscheduled, 2=Started, 3=Completed, 4=Canceled) used to indicate the status of a project.

Key field

A common field shared by linked files used to join files together.

Flat files

Files that store data in plain text format and can be easily created and manipulated using text editors like vi and Emacs.

Variable-record format

File format where records have varying lengths, with a delimiter (such as a colon) between each field.

Flowchart

A visual representation of the logic and steps involved in programmer project assignments, illustrating the flow of data between files.

Awk

A programming language and command used for text processing and generating reports in Unix and Linux environments.

printf function

A function in Awk used for formatted printing, allowing for precise control over the output format.

format

An expression in the printf function that contains literal text and specifications for formatting data fields.

$expr1, $expr2, $expr3

Represent data fields in Awk, typically referring to $1, $2, $3, and so on in the programmer file.

Hands-on Project

Practical exercises that allow for hands-on learning and application of concepts discussed in the text.

Shell Script

A script containing a series of commands that can be executed in a specific order, often used to automate tasks in Unix and Linux systems.

Bourne Again Shell (Bash)

A widely used shell in Linux systems, providing compatibility with the original Bourne shell and additional features.

Comments

Text in a script file that provides explanations, documentation, and notes for users and programmers, marked by the pound (#) character.

Script Execution

Running a shell script in a shell environment, such as using the sh command followed by the script name or making the script executable and running it with ./scriptname.

Shell

The first line of a script where commands are executed.

Shell Script

A script containing commands to be executed in a shell.

Hands-on Project

Practical tasks to apply and practice the concepts learned.

Programmer Activity Status Report

A report detailing the activities of a programmer.

Selection Commands

Commands that extract information from files.

Manipulation and Transformation Commands

Commands that alter and format extracted information.

Grep Command

Searches for a specific pattern in a file.

Uniq Command

Removes duplicate lines from a file.

Comm Command

Compares lines common to two different files.

Diff Command

Determines the minimum set of changes needed to match the contents of two files.

Wc Command

Counts the number of bytes, words, or lines in a file.

Sed Command

A stream editor for making global changes to large files.

Tr Command

Translates characters, substituting or deleting specified characters.

Pr Command

Prints the standard output in pages.

Record Layout

Identifies fields by name and data type in a record.

Logical Structure

Organization of information in files, records, and fields.

Pipe Operator (|)

Redirects the output of one command to the input of another.

Comm Command

A command used to compare two sorted files line by line.

Grep Command

A command used to search for patterns in files.

-r Option

An option in the grep command that enables searching through subdirectories.

Uniq Command

A command used to remove duplicate lines from a sorted file.

Pipe Operator

A symbol (|) used to direct the output of one command as input to another.

Awk Command

A command-line utility for pattern scanning and processing.

Tr Command

A command used for translating or deleting characters.

Pr Command

A command used to paginate or columnate files for printing.

Grep Command

A command-line utility for searching plain-text data sets for lines that match a regular expression.

More Command

A command that allows the user to view text files one screen at a time in the Unix/Linux operating system.

Head Command

A command that outputs the first part of files in Unix/Linux.

Regular Expression

A sequence of characters that define a search pattern, mainly used for pattern matching with strings.

Metacharacter

A character with a special meaning in a regular expression, such as "^" which signifies the beginning of a line.

Pipe Operator

A symbol (|) used to pass the output of one command as input to another command in Unix/Linux.

Uniq Command

A command-line utility that reports or filters out repeated lines in a file.

Comm Command

A command-line utility in Unix/Linux used to compare two sorted files line by line.

diff

A command-line tool used to compare the contents of two files line by line.

UNIX/Linux

Operating systems known for their powerful command-line interface and stability.

wc command

A command-line tool used to count the number of lines, words, and bytes in a file.

sed

A stream editor used to manipulate text files by performing operations like search, replace, and delete on specific lines.

tr command

A command used to translate characters in files, such as converting from lowercase to uppercase letters, deleting specified characters, and replacing characters.

-d option

An option used with the tr command to delete input characters found in string1 from the output.

-s option

An option of the tr command that checks for sequences of a character or string of characters repeated several consecutive times and replaces them with the specified character or string.

pr command

A command used to format files, with options like -h for header and -l for limiting the number of lines per page.

Programmer Activity Status Report

A polished report created through a series of related projects to design and implement various programmer and project reports.

awk command

A command used to manipulate and analyze text files, often used for pattern scanning and processing.

cut command

A command used to extract specific parts of a file, such as fields or columns.

more command

A command used to display the contents of a file one screen at a time.

Awk

A versatile programming language mainly used for pattern scanning and processing.

Cut

A command-line utility used to extract sections from each line of input.

Sort

A command-line utility for sorting lines of text files.

Uniq

A command-line utility that reports or filters out repeated lines in a file.

Comm

A command-line utility for comparing two sorted files line by line.

Join

A command-line utility for combining lines from two files based on a common field.

Sed

A stream editor for filtering and transforming text.