CIS 33A Perl handout week 11 part 2

Preliminary material should be here.

Sample programs from Clare Nguyen (edited by Ira Oldham)

############## shell I/O ############

Lecture week 11 hour 2 Example shell I/O

#########################

### system
system "date";
system "who | head";
$var = "infile";
system "grep 34 $var";

### use ` `
print `pwd`;
foreach $person (`who`)
{
 $count++;
}
print $count,"\n";
$user = `who | head`;
print "as a string: $user\n";
@user = `who | head`;
print "as a list: @user\n";

### use open
open(WHO, "who |") or warn "can't open who: $!\n";
while (<WHO>) { $count ++ }
close WHO;
print "$count\n";

open (LIST, "ls |") or warn "can't open ls: $!\n";
@dir_listing = <LIST>;
close LIST;
print "@dir_listing[0..4]\n";

#open (LPR, "| lpr") or warn "can't open lpr: $!\n";
#print LPR @dir_listing;
#close LPR;