Perhaps this one is, what you are looking for?

C:\Daten\perl>cat match.pl
#!/usr/bin/perl
use strict;
use warnings;

my $var = 'Sensor30';

while (<DATA>) {
    print if /^>?\Q$var\E$/;
}

__DATA__
>Sensor30
>FooSensor30
> Sensor30
Sensor300
Sensor30
>Sensor3


C:\Daten\perl>perl match.pl
>Sensor30
Sensor30

[download]

Without a regular expression: 

C:\Daten\perl>cat match.pl
#!/usr/bin/perl
use strict;
use warnings;

my $var = 'Sensor30';

while (<DATA>) {
    chomp;
    print "$_\n" if $_ eq $var or $_ eq '>' . $var;
}

__DATA__
>Sensor30
>FooSensor30
> Sensor30
Sensor300
Sensor30
>Sensor3


C:\Daten\perl>perl match.pl
>Sensor30
Sensor30

[download]

In reply to Re^2: regex needed by Crian
in thread regex needed by Anonymous Monk

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