Read lines and match against pattern

Here's a quickie for you, simply what we're doing is

Line 1: While reading file into variable line

Line 2: Match a regex, echo the $line if matching the word "bird" echo that line. Do whatever actions you need here, in this if statement.

Line 3: End of while loop, which pipes in the file foo.text

#!/bin/bash
while read line; do
  if [[ $line =~ bird ]] ; then echo $line; fi
done <foo.text

Note that "bird" is a regex. So that you could replace it with for example: bird.*word to match the same line with a regular expression.

Try it with a file like so, called foo.text with the contents:

my dog is brown
her cat is white
the bird is the word

The easier way to do this, is using grep (or egrep).

grep bird file.txt