You should end up with a file called bysent that contains something like this:
#!/usr/bin/perl
#Set perl to paragraph mode and multiline matches.
$/ = ""; #paragraph mode
$* = 1; #multiline matches
#Open the input file.
open(INPUT, "senttest");
#Open the output file.
open(OUTPUT, ">senttest.out");
#While there are paragraphs in the input file, take them one at a time and:
while (<INPUT>) {
# Reformat them.
s/\n/ /g; #replace all existing newlines with space
s/\. /\.\n/g; #put a newline after all periods, and get rid of the extra space
# Print them to the output file.
print OUTPUT;
}
#Close the input and output files.
close(INPUT);
close(OUTPUT);