Overview

Teaching: 15 min
Exercises: 0 min

Questions

• How can I save and re-use commands?

Objectives

• Use find to find files whose names match simple patterns.

This Martin Bishop character is beginning to look rather suspicious. It’s time we look into the email communication between Dr Gill and Mr Bishop.

The emails directory

All of Dr Gill’s emails are in the emails directory.

$ ls emails/

Oh dear, there are a lot of directories. The emails have been grouped by the day that they were sent or received. Let’s have a look in one of them.

$ ls emails/01_01_2017

It would appear each email is its own file. And they are named “RECEIVED_FROM_” or “SENT_TO_” and then the person’s name and time.

We need a tool to be able to search for a specific file.

Finding files.

We’ve already covered finding things in a single file using grep. Now we cover finding files within a file system using find. This is another very powerful file.

It takes one main argument, a directory to search, and many more arguments that define the filters use to display the files.

Let’s see it without a filter:

$ find email_summaries/

It will print out every file or directory within the email_summaries directory, and go into each subdirectory.

Let’s try it with the -name filter. We specify a pattern, using a wildcard if we want, to find files or directories that match.

$ find email_summaries/ -name 'Joan*'

The Manual

On most linux machine, there is a man command that gives you the manual for a command. Some commands don’t use --help and some don’t have a manual page. Unfortunately git for windows doesn’t support man. In that cause, a quick Google search for “man page” plus the name of the command will provide the relevant information.

Another filter is -type. To filter for files:

$ find email_summaries/ -type f

And to filter for directories:

$ find email_summaries/ -type d

Email Time

Now let’s see if we can find all the emails sent to Martin Bishop.

$ find emails/ -name 'SENT_TO_Martin_Bishop*'

That’s a lot of emails. We could count them by piping find in wc -l

$ find emails/ -name 'SENT_TO_Martin_Bishop*' | wc -l

108

This says that Dr Gill emailed Martin Bishop 108 times and matches up with the email summaries file.

Exercise

Find all the email received from Martin Bishop. Is there anything suspicious about the result?

Solution

$ find emails/ -name 'RECEIVED_FROM_Martin_Bishop*'

Key Points

• find finds files with specific properties that match patterns.