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Hands-On Data Science with the Command Line

You're reading from   Hands-On Data Science with the Command Line Automate everyday data science tasks using command-line tools

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Product type Paperback
Published in Jan 2019
Publisher Packt
ISBN-13 9781789132984
Length 124 pages
Edition 1st Edition
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Authors (3):
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Jason Morris Jason Morris
Author Profile Icon Jason Morris
Jason Morris
Raymond Page Raymond Page
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Raymond Page
Chris McCubbin Chris McCubbin
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Chris McCubbin
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Toc

It's the end of the world as we know it while and until

Let's explore two more options for assisting with iteration. The while construct allows for the repetitive execution of a list or set of commands as long as the command that controls the while loop exits successfully. Let's see an example:

Let's say I wanted to print the "hello!" string four times in a script—no more and no less. We can do so with the following:

Let's save and run this script to see what happens.

Don't forget to chmod -x these scripts to make them executable.

Executing the script produces the following:

Notice that, in the script, we created a variable called i="0". This sets the i variable to zero. Do you see the while [ $i -lt 4 ] block? This allows us to run the loop as the i variable is less than the 4 integer. Go ahead and play around with this...

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