first-last

This collection of bash scripts aims to improve readability in complex bash scripts that involve piped data processing. It provides a set of convenient utilities to extract specific elements from piped input, simplifying data manipulation.

Utils

first / 1, second / 2, third / 3, ...

These utilities retrieve the corresponding element from the piped input:

echo "one two three four five six seven eight nine ten" | first
one

Alternatively, you can use numeric equivalents like 1, 2, 3, and so on:

echo "one two three four five six seven eight nine ten" | 1
one

You can use select any element from 1 to 10.

last-utils

Additionally, the last utility retrieves the last element from the input. To access the elements in reverse order, you can use last-1, last-2, last-3, and so on.

last

$ echo "one two three four five six" | last
six

last-1

$ echo "one two three four five six" | last-1
five

last-2

$ echo "one two three four five six" | last-2
four

last-3

$ echo "one two three four five six" | last-3
three

last-4

$ echo "one two three four five six" | last-4
two

last-5

$ echo "one two three four five six" | last-5
one

Installation

Copy the scripts somewhere and chmod +x

Tests

You can run the provided test suite to validate the functionality of each utility. The test results will be displayed, indicating whether each test passed or failed, represented by a green tick (✓) for passed tests.

$ ./test
Testing 'first':
✓ Test passed

Testing 'second':
✓ Test passed

Testing 'third':
✓ Test passed

Testing 'fifth':
✓ Test passed

Testing 'sixth':
✓ Test passed

Testing 'seventh':
✓ Test passed

Testing 'eighth':
✓ Test passed

Testing 'ninth':
✓ Test passed

Testing 'tenth':
✓ Test passed

Testing 'last':
✓ Test passed

Testing 'last-1':
✓ Test passed

Testing 'last-2':
✓ Test passed

Testing 'last-3':
✓ Test passed

Testing 'last-4':
✓ Test passed

Testing 'last-5':
✓ Test passed