Extracting-Components-from-a-Unix-Style-Date

Submitted by admin on Fri, 2007-06-22 10:41

4.6.2  Extracting Components from a Unix-Style Date

 Now, we present another example that illustrates remembering results of pattern matching. Here, we assume we are on a Unix machine. Using backticks, we call the Unix date command which returns something like the following.

 

Mon Aug 17 19:17:00 MDT 1998

 

In this program, we match over a string that contains such a date string. The pattern expression has ten starting parentheses and ten closing parentheses. Therefore, ten variables, $1 through $10 are set. The matched substrings are remembered and stored in the array @fields. In the assignment statements that follow, sometimes we assign from a numbered variable and sometimes from an element of @fields.

 Program 4.22 

#!/usr/bin/perl

$date = `date`;
@fields = 
  ($date =~ /^(\w+) ((\w+) (\d+)) ((..):(..):(..)) (\w+) (\d+)/);
$day = $1; 
$monthdate = $2; $month = $3; $date = $4; 
$time = $5; $hour = $fields[5]; 
$minutes = $fields[6]; $seconds = $fields[7];
$timeZone = $9; 
$year = $10;

print "Day = $day\nMonth and  Day = $monthdate\n";
print "Month = $month\nDate = $date\n";
print "Time = $time\nHour = $hour\n";
print "Minutes = $minutes\nSeconds = $seconds\n";
print "Time Zone = $timeZone\nYear = $year\n";