Perl One-Liners: 130 Programs That Get Things Done [NOOK Book]

Overview


Part of the fun of programming in Perl lies in tackling tedious tasks with short, efficient, and reusable code. Often, the perfect tool is the one-liner, a small but powerful program that fits in one line of code and does one thing really well.


In Perl One-Liners, author and impatient hacker Peteris Krumins takes you through more than 100 compelling one-liners that do all sorts of handy things, such as ...

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Perl One-Liners: 130 Programs That Get Things Done

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Overview


Part of the fun of programming in Perl lies in tackling tedious tasks with short, efficient, and reusable code. Often, the perfect tool is the one-liner, a small but powerful program that fits in one line of code and does one thing really well.


In Perl One-Liners, author and impatient hacker Peteris Krumins takes you through more than 100 compelling one-liners that do all sorts of handy things, such as manipulate line spacing, tally column values in a table, and get a list of users on a system. This cookbook of useful, customizable, and fun scripts will even help hone your Perl coding skills, as Krumins dissects the code to give you a deeper understanding of the language.


You'll find one-liners that:

  • Encode, decode, and convert strings
  • Generate random passwords
  • Calculate sums, factorials, and the mathematical constants π and e
  • Add or remove spaces
  • Number lines in a file
  • Print lines that match a specific pattern
  • Check to see if a number is prime with a regular expression
  • Convert IP address to decimal form
  • Replace one string with another

And many more! Save time and sharpen you coding skills as you learn to conquer those pesky tasks in a few precisely placed keystrokes with Perl One-Liners.
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Product Details

  • ISBN-13: 9781593275693
  • Publisher: No Starch Press San Francisco, CA
  • Publication date: 11/13/2013
  • Sold by: Barnes & Noble
  • Format: eBook
  • Sales rank: 734,834
  • File size: 2 MB

Meet the Author

Peteris Krumins is a programmer, systems administrator, start-up manager, and all-around hacker. He is the cofounder of Browserling and Testling, and he runs the popular programming blog catonmat.net.

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Table of Contents

About the Author;
About the Technical Reviewer;
Acknowledgments;
Chapter 1: Introduction to Perl One-Liners;
Chapter 2: Spacing;
2.1 2.1 Double-space a file;
2.2 2.2 Double-space a file, excluding the blank lines;
2.3 2.3 Triple-space a file;
2.4 2.4 N-space a file;
2.5 2.5 Add a blank line before every line;
2.6 2.6 Remove all blank lines;
2.7 2.7 Remove all consecutive blank lines, leaving only one;
2.8 2.8 Compress/expand all blank lines into N consecutive lines;
2.9 2.9 Double-space between all words;
2.10 2.10 Remove all spacing between words;
2.11 2.11 Change all spacing between words to one space;
2.12 2.12 Insert a space between all characters;
Chapter 3: Numbering;
3.1 3.1 Number all lines in a file;
3.2 3.2 Number only non-empty lines in a file;
3.3 3.3 Number and print only non-empty lines in a file (drop empty lines);
3.4 3.4 Number all lines but print line numbers only for non-empty lines;
3.5 3.5 Number only lines that match a pattern; print others unmodified;
3.6 3.6 Number and print only lines that match a pattern;
3.7 3.7 Number all lines but print line numbers only for lines that match a pattern;
3.8 3.8 Number all lines in a file using a custom format;
3.9 3.9 Print the total number of lines in a file (emulate wc -l);
3.10 3.10 Print the number of non-empty lines in a file;
3.11 3.11 Print the number of empty lines in a file;
3.12 3.12 Print the number of lines in a file that match a pattern (emulate grep -c);
3.13 3.13 Number words across all lines;
3.14 3.14 Number words on each individual line;
3.15 3.15 Replace all words with their numeric positions;
Chapter 4: Calculations;
4.1 4.1 Check if a number is a prime;
4.2 4.2 Print the sum of all fields on each line;
4.3 4.3 Print the sum of all fields on all lines;
4.4 4.4 Shuffle all fields on each line;
4.5 4.5 Find the numerically smallest element (minimum element) on each line;
4.6 4.6 Find the numerically smallest element (minimum element) over all lines;
4.7 4.7 Find the numerically largest element (maximum element) on each line;
4.8 4.8 Find the numerically largest element (maximum element) over all lines;
4.9 4.9 Replace each field with its absolute value;
4.10 4.10 Print the total number of fields on each line;
4.11 4.11 Print the total number of fields on each line, followed by the line;
4.12 4.12 Print the total number of fields on all lines;
4.13 4.13 Print the total number of fields that match a pattern;
4.14 4.14 Print the total number of lines that match a pattern;
4.15 4.15 Print the number π;
4.16 4.16 Print the number e;
4.17 4.17 Print UNIX time (seconds since January 1, 1970, 00:00:00 UTC);
4.18 4.18 Print Greenwich Mean Time and local computer time;
4.19 4.19 Print yesterday’s date;
4.20 4.20 Print the date 14 months, 9 days, and 7 seconds ago;
4.21 4.21 Calculate the factorial;
4.22 4.22 Calculate the greatest common divisor;
4.23 4.23 Calculate the least common multiple;
4.24 4.24 Generate 10 random numbers between 5 and 15 (excluding 15);
4.25 4.25 Generate all permutations of a list;
4.26 4.26 Generate the powerset;
4.27 4.27 Convert an IP address to an unsigned integer;
4.28 4.28 Convert an unsigned integer to an IP address;
Chapter 5: Working With Arrays and Strings;
5.1 5.1 Generate and print the alphabet;
5.2 5.2 Generate and print all the strings from “a” to “zz”;
5.3 5.3 Create a hex lookup table;
5.4 5.4 Generate a random eight-character password;
5.5 5.5 Create a string of specific length;
5.6 5.6 Create an array from a string;
5.7 5.7 Create a string from the command-line arguments;
5.8 5.8 Find the numeric values for characters in a string;
5.9 5.9 Convert a list of numeric ASCII values into a string;
5.10 5.10 Generate an array with odd numbers from 1 to 100;
5.11 5.11 Generate an array with even numbers from 1 to 100;
5.12 5.12 Find the length of a string;
5.13 5.13 Find the number of elements in an array;
Chapter 6: Text Conversion and Substitution;
6.1 6.1 ROT13 a string;
6.2 6.2 Base64-encode a string;
6.3 6.3 Base64-decode a string;
6.4 6.4 URL-escape a string;
6.5 6.5 URL-unescape a string;
6.6 6.6 HTML-encode a string;
6.7 6.7 HTML-decode a string;
6.8 6.8 Convert all text to uppercase;
6.9 6.9 Convert all text to lowercase;
6.10 6.10 Uppercase only the first letter of each line;
6.11 6.11 Invert the letter case;
6.12 6.12 Title-case each line;
6.13 6.13 Strip leading whitespace (spaces, tabs) from the beginning of each line;
6.14 6.14 Strip trailing whitespace (spaces, tabs) from the end of each line;
6.15 6.15 Strip whitespace (spaces, tabs) from the beginning and end of each line;
6.16 6.16 Convert UNIX newlines to DOS/Windows newlines;
6.17 6.17 Convert DOS/Windows newlines to UNIX newlines;
6.18 6.18 Convert UNIX newlines to Mac newlines;
6.19 6.19 Substitute (find and replace) “foo” with “bar” on each line;
6.20 6.20 Substitute (find and replace) “foo” with “bar” on lines that match “baz”;
6.21 6.21 Print paragraphs in reverse order;
6.22 6.22 Print all lines in reverse order;
6.23 6.23 Print columns in reverse order;
Chapter 7: Selectively Printing and Deleting Lines;
7.1 7.1 Print the first line of a file (emulate head -1);
7.2 7.2 Print the first 10 lines of a file (emulate head -10);
7.3 7.3 Print the last line of a file (emulate tail -1);
7.4 7.4 Print the last 10 lines of a file (emulate tail -10);
7.5 7.5 Print only lines that match a regular expression;
7.6 7.6 Print only lines that do not match a regular expression;
7.7 7.7 Print every line preceding a line that matches a regular expression;
7.8 7.8 Print every line following a line that matches a regular expression;
7.9 7.9 Print lines that match regular expressions AAA and BBB in any order;
7.10 7.10 Print lines that don’t match regular expressions AAA and BBB;
7.11 7.11 Print lines that match regular expression AAA followed by BBB followed by CCC;
7.12 7.12 Print lines that are at least 80 characters long;
7.13 7.13 Print lines that are fewer than 80 characters long;
7.14 7.14 Print only line 13;
7.15 7.15 Print all lines except line 27;
7.16 7.16 Print only lines 13, 19, and 67;
7.17 7.17 Print all lines from 17 to 30;
7.18 7.18 Print all lines between two regular expressions (including the lines that match);
7.19 7.19 Print the longest line;
7.20 7.20 Print the shortest line;
7.21 7.21 Print all lines containing digits;
7.22 7.22 Print all lines containing only digits;
7.23 7.23 Print all lines containing only alphabetic characters;
7.24 7.24 Print every second line;
7.25 7.25 Print every second line, beginning with the second line;
7.26 7.26 Print all repeated lines only once;
7.27 7.27 Print all unique lines;
Chapter 8: Useful Regular Expressions;
8.1 8.1 Match something that looks like an IP address;
8.2 8.2 Test whether a number is in the range 0 to 255;
8.3 8.3 Match an IP address;
8.4 8.4 Check whether a string looks like an email address;
8.5 8.5 Check whether a string is a number;
8.6 8.6 Check whether a word appears in a string twice;
8.7 8.7 Increase all integers in a string by one;
8.8 8.8 Extract the HTTP User-Agent string from HTTP headers;
8.9 8.9 Match printable ASCII characters;
8.10 8.10 Extract text between two HTML tags;
8.11 8.11 Replace all tags with ;
8.12 8.12 Extract all matches from a regular expression;
Perl’s Special Variables;
A.1 Variable $_;
A.2 Variable $.;
A.3 Variable $/;
A.4 Variable $;
A.5 Variables $1, $2, $3, and so on;
A.6 Variable $,;
A.7 Variable $";
A.8 Variable @F;
A.9 Variable @ARGV;
A.10 Variable %ENV;
Using Perl One-Liners On Windows;
B.1 Perl on Windows;
B.2 Bash on Windows;
B.3 Perl One-Liners in Windows Bash;
B.4 Perl One-Liners in the Windows Command Prompt;
B.5 Perl One-Liners in PowerShell;
Perl1Line.Txt;
C.1 Spacing;
C.2 Numbering;
C.3 Calculations;
C.4 Working with Arrays and Strings;
C.5 Text Conversion and Substitution;
C.6 Selectively Printing and Deleting Lines;
C.7 Useful Regular Expressions;
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