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Using grep with Perl

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Let's say you have an array named fruit that contains values, such as apple, orange, and banana.

@fruit = qw(apple orange banana pineapple);

 

Printing this array will display apple, orange, banana, and pineapple.

print @fruit;

 


Contains

If you only want to print fruit that contains the string "apple", grep can be used. This will print both "apple" and "pineapple".

print grep(/apple/, @fruit);

 

Since this uses forward slashes, if the value being checked contains forward slashes, you will need to escape the forward slashes.

print grep(/\/path\/to\/directory/, @fruit);

 


Does not contain

Use an exclamation point to return items to do not match. In this example, only fruit that does not contain "apple" will be printed.

print grep(!/apple/, @fruit);

 


Exact match

If you want to only return exact matches, us this syntax. In this example, "apple" will be printed and "pineapple" will not be printed.

foreach my $fruit (@fruit) {
  if (grep { $fruit eq "apple" } @fruit) {
    print $fruit;
  }
}

 


Is not an exact match

Use "ne" (not equal) to return items to do not match. In this example, only fruit that does not match "apple" will be printed.

foreach my $fruit (@fruit) {
  if (grep { $fruit ne "apple" } @fruit) {
    print $fruit;
  }
}

 


Grep the array

Grep can be used to update the array to only have the values that contain or match the grep expression.

@fruit = grep(/apple/, @fruit);

@fruit = grep { $_ eq "apple" } @fruit;

 


Variable

The Perl grep function cannot be stored in a variable. Instead, an if statement can be used.

foreach my $fruit (@fruit) {
  if ($fruit =~ "apple") { 
    my $apple_fruit = $fruit; 
  }
}

 

 



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