Making the Computer Work for You

Programming for non-programmers

G. Wade Johnson

Houston.pm

Pre-requisites

• Familiar with a text editor
• Familiar with a command line
• Can run programs on the command line

Core Concepts

Computers are dumb, but fast.

Core Concepts

One-shot programs don't have to be efficient.

Core Concepts

Let the computer do the boring, repetitive stuff.

Core Concepts

A series of simple steps is better than a complicated solution.

Core Concepts

It's more important to solve the problem than to perfect the program.

Core Programming Concepts

1. Sequence
2. Variables
3. Conditionals
4. Iteration
5. Subroutines

Writing

• Not everyone can write a novel, screenplay, or technical manual.
• Not everyone can write a short story.
• Almost everyone can handle a todo list or thank you note.
• Most people can write a paragraph.

Programming is Like Writing

• Not everyone can write a production program with 24/7 up-time.
• Not everyone can write a word processor.
• Almost everyone can handle putting a series of commands in a shell script or batch file.
• Most people can handle a simple script.

Problem 1

Start a set of programs

   prog1
   prog2
   prog3

Problem 2

Find a string in a file

   grep special_string junk.txt

Problem 2a

Find a string in multiple files.

   grep special_string *.txt

Problem 3

Find a number of a certain type in a file.

• A negative number
• A number less than 1000
• A number greater than 1284000000

Example: findit.pl Perl script

Problem 4

Append a line to a set of files.

Example: append_copyright bash script

Problem 5

Insert a line in multiple files.

Example: insert_copyright.pl Perl script

Problem 6

Delete a particular line from a file.

Example: delete_copyright.pl Perl script

Core Incantation

The solution to the last three problems follows the same form.

Problem 7

Rename a set of files based on some criteria

DSCN####.JPG -> Vacation-yyyymmdd-hhmmss-####-wade.jpg

Example: renphoto.pl Perl script

Problem 8

Perform the same action on a set of files obtained from another program.

We didn't get this far.

Problem 9

Code generation

We didn't get this far.