[Chapter 45] 45.16 Standard Input to a for Loop
Author: Jerry Peek, Tim O'Reilly & Mike Loukides
Date: 1998-08-04T21:54:39Z

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| Chapter 45 Shell Programming for the Initiated |

## 45.16 Standard Input to a for Loop

An obvious place to use a Bourne shell for loop (44.16) is to step through a list of arguments - from the command line or a variable. But combine the loop with backquotes (9.16) and cat (25.2), and the loop will step through the words on standard input.

Here's an example:

>     for x in `cat`
>     do
>         ...handle $x
>     done

Because this method splits the input into separate words, no matter how many words are on each input line, it can be more convenient than a while loop running the read command, as in article 9.20. When you use this script interactively though, the loop won't start running until you've typed all of the input; using while read will run the loop after each line of input.

- JP

45.15 How to Unset all Command-Line Parameters |  | 45.17 Making a for Loop with Multiple Variables