Jeremie Charlet

10 06 2015

Introduction to Shell Scripting

Introduction

Why use the shell?(copy/paste from “Why automate?” slide from “Getting Started with Puppet - PuppetConf

2013” https://www.youtube.com/watch?v=TdAmAj3eaFI)

•Speed•Consistency•To get to fun things

3

PLAN

Demonstration and quick displays of code on the following topics:

1.Start simple: analyse some logs2.Write your own scripts3.Reuse your scripts to do automation

5

1. Start simple: to analyse logs

Read the logs of one batch application•Find out if there are any errors•List the document ids in error

Check whether those documents exists in the collection

6

Useful commandsLsEchowc -l

Cat / more / less

touchVi / vim / emacs

Grep / egrep / zgrepFind

AwkSedCut

Xargs

HostWgetCurl

Watchps

MongoJavaMysqlgit

7

2. Write scripts

From simple naïve scripts:

To more complex stuff:

8

A few hints

• Add colours to your shell

• If you do something frequently…….…… write a script

• Get the job done, do not polish it, you will get to it on next time

9

Happy Consequences

• You do not prevent yourself from writing scripts because it is going to take ages

• You progress and learn gradually, over time

• You stop looking for big tools, you answer simple needs with simple solutions

> Example: Monitoring tool for daily updates on categories

10

3. Reuse your scripts to do automation

Sample with the Monitoring tool

Cron (scheduled task) ran every day

Script to monitor: monitorDailyUpdates.sh

Dependencies:• checkDailyUpdates.sh• sendMail.sh

11