Perl <> 符号

<> 行输入符读取数据流
[oracle@dwh1 perl]$ cat 4.pl 
#!/usr/bin/perl
print "This is my first perl programn";
$a=<>; ## 从控制台读入字符窜
print $a;
[oracle@dwh1 perl]$ perl 4.pl 
This is my first perl program
aaaaaa
aaaaaa

从控制台读取,再打印一次



open my ($fh),'<',"1.txt";
foreach (<$fh>) {
print "$_";
}

[oracle@dwh1 perl]$ cat 7.pl 
open my ($fh),"1.txt";
my @f = <$fh>;
print "@f";

[oracle@dwh1 perl]$ perl 7.pl 
aaaaaaaa
 bbbbbbbb
 cccccccc
 dddddddd
 eeeeeeee
 ffffffff
 gggggggg


单词边界:
[oracle@dwh1 perl]$ cat 8.pl 
my $a = "1shanghai";
if ($a =~ /bshanghaib/){print "22222n"};
[oracle@dwh1 perl]$ vi 8.pl
[oracle@dwh1 perl]$ cat 8.pl 
my $a = "1shanghai";
if ($a =~ /bshanghaib/){print "22222n"};
[oracle@dwh1 perl]$ perl 8.pl 
[oracle@dwh1 perl]$ 

[oracle@dwh1 perl]$ cat 8.pl 
my $a = "shanghai1";
if ($a =~ /bshanghaib/){print "22222n"};
[oracle@dwh1 perl]$ perl 8.pl 
[oracle@dwh1 perl]$ 

[oracle@dwh1 perl]$ cat 8.pl 
my $a = "shanghain";
if ($a =~ /bshanghaib/){print "22222n"};
[oracle@dwh1 perl]$ perl 8.pl 
22222

[oracle@dwh1 perl]$ cat 8.pl 
my $a = "nshanghai";
if ($a =~ /bshanghaib/){print "22222n"};
[oracle@dwh1 perl]$ perl 8.pl 
22222