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fakedata

fakedata is a small program that generates random data on the command line.

Table Of Contents

Overview

Quick Start

fakedata helps you generate random data in various ways. You can generate data by specifying on the command line the kind of data you need:

$ fakedata email country
[email protected] Afghanistan
[email protected] Turkey
[email protected] Saint Helena
[email protected] Montenegro
[email protected] Croatia
[email protected] Vietnam
[email protected] Lithuania
[email protected] Haiti
[email protected] Malaysia
[email protected] Virgin Islands, British

Be default, fakedata generates data using a space as a separator. You can choose a different output format like CSV:

$ fakedata --format=csv product.category product.name
Shoes,Rankfix
Automotive,Namis
Movies,Matquadfax
Tools,Damlight
Computers,Silverlux
Industrial,Matquadfax
Home,Sil-Home
Health,Toughwarm
Shoes,Freetop
Tools,Domnix

or SQL insert statements:

$ fakedata --format=sql --limit 1 email domain
INSERT INTO TABLE (email,domain) values ('[email protected]','example.me');

You can specify the name of the column using a field with the following format column_name=generator:

$ fakedata --format=sql --limit 1 login=email referral=domain
INSERT INTO TABLE (login,referral) values ('[email protected]','test.me');

If you need some control over the output, you can use templates:

$ echo '{{Email}}--{{Int}}--{{Color}}' | fakedata -l5
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]

Why another random data generator?

fakedata focuses on a simple UI (if you think it could be simpler, please let us know! We ❤️ feedback!) and the ability to fully control both the output format (using templates) and the set of values a generator will pick from. We call this feature "generators' constraints" and it's explained in detail here.

Generators

fakedata provides a number of generators. You can see the full list running the following command:

$ fakedata --generators # or -G
color             one word color
country           Full country name
country.code      2-digit country code
date              date
domain            domain
domain.tld        example|test
# ...
# It's a long list :)

You can use the -g (or --generator) option to see an example:

$ fakedata -g sentence
Description: sentence

Example:

Jerk the dart from the cork target.
Drop the ashes on the worn old rug.
The sense of smell is better than that of touch.
Tin cans are absent from store shelves.
Shut the hatch before the waves push it in.

Constraints

Some generators allow you to pass in a range to constraint the output to a subset of values. To find out which generators support constraints:

$ fakedata -c # or fakedata --generators-with-constraints

Int

Here is how you can use constraints with the int generator:

$ fakedata int:1,100 # will generate only integers between 1 and 100
$ fakedata int:50, # specifying only min number works too
$ fakedata int:50 # also works

Enum

The enum generator allows you to specify a set of values. It comes handy when you need random data from a small set of values:

$ fakedata --limit 5 enum
foo
baz
foo
foo
baz
$ fakedata --limit 5 enum:bug,feature,question,duplicate
question
duplicate
duplicate
bug
feature

When passing a single value enum can be used to repeat a value in every line:

$ fakedata --limit 5 enum:one,two enum,repeat
two repeat
one repeat
two repeat
one repeat
one repeat

File

The file generator can be use to read custom values from a file:

$ printf "one\ntwo\nthree" > values.txt
$ fakedata -l5 file:values.txt
three
two
two
one
two

Templates

fakedata supports parsing and executing template files for generating customized output formats. fakedata executes the provided template a number of times based on the limit flag (-l, --limit) and writes the output to stdout, exactly like using inline generators.

fakedata can read templates from disk:

$ echo "{{Email}}--{{Int}}" > /tmp/template.tmpl
$ fakedata --template /tmp/template.tmpl
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]

Or you can pipe the template into fakedata:

$ echo "#{{ Int 0 100}} {{ Name }} <{{ Email }}>" | fakedata
#56 Dannie Martin <[email protected]>
#89 Moshe Walsh <[email protected]>
#48 Buck Reid <[email protected]>
#55 Rico Powell <[email protected]>
#92 Luise Wood <[email protected]>
#30 Isreal Henderson <[email protected]>
#96 Josphine Patton <[email protected]>
#95 Jetta Blair <[email protected]>
#10 Clorinda Parsons <[email protected]>
#0 Dionna Bates <[email protected]>

Generators

The generators listed under fakedata -g are available as functions into the templates. If the generator name is a single word, then it's available as a function with the same name capitalized (example: int becomes Int). If the generator name is composed by multiple words joined by dots, then the function name is again capitalized by the first letter of the word and joined together (example: product.name becomes Product.Name).

Each generator with constraints is available in templates as a function with arguments.

Enum

Enum takes one or more strings and returns a random string on each run. Strings are passed to Enum like so:

{{ Enum "feature" "bug" "documentation" }}

This Enum will return either the string feature, bug, or documentation for each run.

File

File reads a file from disk and returns a random line on each run. It takes one parameter which is the path to the file on disk.

{{ File "/var/data/dummy/dummy.txt" }}

Int

Int takes one or two integer values and returns a number within this range. By default it returns a number between 0 and 1000.

echo "{{ Int 15 20 }}" | fakedata -l5
15
20
15
15
17

Date

Date takes one or two dates and returns a date within this range. By default, it returns a date between one year ago and today.

Helpers

Beside the generator functions, fakedata templates provide a set of helper functions:

  • Loop
  • Odd
  • Even

If you need to create your own loop for advanced templates you can use the {{ Loop }} function. This function takes a single integer as parameter which is the number of iterations. Loop has to be used with range e.g.

{{ range Loop 10 }}
  I am printed 10 times!
{{ end }}

Loop can take a second argument, so that you can specify a range and fakedata will generate a random number of interations in that range. For example:

{{ range Loop 1 5 }}42{{ end }}

In combination with Loop and range you can use Odd and Even to determine if the current iteration is odd or even. This is especially helpful when creating HTML tables:

{{ range $i, $j := Loop 5 }}
<tr>
  {{ if Odd $i -}}
  <td class="odd">
    {{- else -}}
  <td class="even">
    {{- end -}}
    {{ Name }}
  </td>
</tr>
{{ end }}

By using Odd we can create tables with a class name of odd and even when generating our HTML. Odd takes an integer as parameter which is why we need to assign the return values of Loop 5 to the variables $i and $j.

Beside the helper function Loop, Odd, and Even templates also support manipulation with printf. By using printf we can create a custom output, for example to display a full name in the format Lastname Firstname instead of Firstname Lastname.

{{ printf "%s %s" NameLast NameFirst }}

Completion

fakedata supports basic shell tab completion for bash, zsh, and fish shells:

$ eval "$(fakedata --completion zsh)"
$ eval "$(fakedata --completion bash)"
$ eval (fakedata --completion fish)

How to install

Homebrew

fakedata can be installed through Homebrew:

$ brew install lucapette/tap/fakedata

Standalone

fakedata can be installed as an executable. Download the latest compiled binary and put it anywhere in your executable path.

Source

Please refer to our contributing guidelines to build and install fakedata from the source.

How to contribute

We love every form of contribution! Good entry points to the project are:

If you're not sure where to start, please open a new issue and we'll gladly help you get started.

Code of Conduct

You are expected to follow our code of conduct when interacting with the project via issues, pull requests or in any other form. Many thanks to the awesome contributor covenant initiative!

License

MIT License Copyright (c) [2017] Luca Pette


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