Execute tail -f and watch a specific line on a remote host.

rtail.sh

#!/bin/bash

TARGET_HOST=localhost
TARGET_FILE=/tmp/test.log
TARGET_LINE='^CRIT'

ssh $TARGET_HOST perl <<_EOF_
    use strict;
    use warnings;
    
    use File::Tail;
    \$| = 1;
    
    my \$file = File::Tail->new(
        name        => '$TARGET_FILE',
        maxinterval => 1
    );
    
    while (my \$line = \$file->read()) {
        print \$line;
        
        if (\$line =~ /$TARGET_LINE/) {
            last;
        }
    }
_EOF_