How to Bash Your Plain Text Foes

Jenny interrogates you

• About your shell experience: none? a little? lots?
• Have you programed before?

Agenda

• Getting around the with bash
• Copying stuff
• Philosophy of POSIX tools
• Finding files
• Regular expressions: How do they work?
• Working with text

Agenda

Getting around

# Where am I?
$ pwd

# What's here?
$ ls
$ ls -al

# Go somewhere
$ cd foo
# Go back
$ cd ..

# Directory stack
$ pushd foo
$ popd

# Make directory
$ mkdir foo

Magic stuff

• up arrow to get previous commands
• tab completes things
• ctrl + a and ctrl + e move around the line

File stuff

# Copy a file
$ cp foo.txt bar.txt

# Move a file
$ mv foo.txt bar.txt

# Download a file
$ curl http://example.com > foo.html

Exercise

There are some plays here: http://mimming.com/presos/how-to-bash-your-plain-text-foes/shakes/

Philosophy break

Philosophy of POSIX tools

Philosophy of POSIX tools

• Worse is better
• Simple tools. Combine them.
• The magic pipe | It glues stuff together

$ cat foo.txt | grep bar

Figuring out a tool

# The help parameter
$ ls --help
ls: illegal option -- -
usage: ls [-ABCFGHLOPRSTUW...] [file ...]

# Google and StackOverflow
$ open https://www.google.com/#q=ls+bash

# man pages
$ man ls
# Waaay too much info
# The 'q' key exits

Exercise

There is a strange command called yes. Figure out what it does.

Finding stuff

# Display file contents
$ cat macbeth.txt

# Filter lines
$ grep 'Thou' macbeth.txt
# OR
$ cat macbeth.txt | grep 'Thou'

# Find files
$ find ./
$ find ./ | grep 'mac'

Exercise

• Display lines in Macbeth that contain 'thou'
• Find all downloaded files that contain 'a' in their name (hint: you need both find and grep)
• Display lines in Macbeth that contain 'sycamore' or 'evermore'

Regular expressions

a.k.a. fancy matchers

• [0-9]
• [a-zA-Z]
• [tT]hou
• ACT [IVX]*
• .

Execrise!

• Display lines in Macbeth that contain 'thou' or 'Thou'
• Bonus: Display lines that contain a tab character

Working with text

• cat - file to stream
• egrep - enhanced grep but with regex - work with lines
• tr - character swapper
• sed - run regexes on a stream
• awk - column manipulator

Working with text

• wc - count stuff
• sort - sorts stuff (and uniques)
• more - look before you leap
• xargs - turn standard output into arguments
• > - stream to a file

All the stuff at once exercises

• count the words in Shakespeare's complete works
  • remove numbers
  • remove punctuation
• Count the number of words that end in 'ed' in Shakespeare's complete works
• Use history command to count number of times you used the 'cd' command
• Your requests!

THE END

These slides

mimming.com/presos/how-to-bash-your-plain-text-foes

Contact me

google.com/+mimming

@MimmingCodes

Questions?