The Command Line Interface is powerful

A little bit of terminology

• Command Line Interface (CLI): This is a user interface that lets you interact with a computer. It is a legacy from the early days of computers. Now a days computers have graphical user interfaces instead (MacOSX, Windows, Linux, …)
• Terminal: It is a an application that lets you run a command line interface. It used to be a physical machine connected to a mainframe computer
• Shell: It is the program that runs the command line. There are many different shells, the most common being bash (Bourne Again SHell) which is installed by default in many Linux distributions

Why should I learn about bash !?

# Clone this repository
cd ~
mkdir github
cd github
git clone "https://github.com/brunj7/eds214-handson-cli.git"
cd eds214-handson-cli
ls
cd _data/babynamesbystate
pwd

# List all the TXT files
ls *.TXT

# Do I have all the states?
ls *.TXT | wc -l  # wait whaaaht!? you can pipe!

# Look at the files
head CA.TXT
tail CA.TXT

# Want to know the most frequent ones over all the years?
sort -k5 -n -t "," CA.TXT 

# A little long, but wait remeber you can pipe things!
sort -k5 -n -t "," CA.TXT | tail

# Concatenate all the files into one master data set
touch baby_allstates.csv     # create an empty file
echo "state, gender, year, firstname, count" > baby_allstates.csv  # add the header to the file
cat *.TXT >> baby_allstates.csv    # append the content of the files to the csv file

Did you know you can actually run Rfrom the command line:

R    # (ctrl + D to get out of it)

Or an R script:

Rscript 10min-loop.R   # (ctrl + C to kill the process)

And yes, you can run python as well:

python   # (ctrl + D to get out of it)

But this is for next week 🙂

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