perl /g

[oracle@oadb test]$ cat t2.pl my $str='1a2';if ($str =~ /[b]*/){print "1111111111\n"};[oracle@oadb test]$ cat t2.pl my $str='1a2';if ($str =~ /[b]*/){print "1111111111\n"};[oracle@oadb test]$ perl t2.pl 1111111111匹配 0 次或多次b[oracle@oadb test]$ cat t2.pl my $str='1a2';if ($str =~ /[b]?/){print "1111111111\n"};[oracle@oadb test]$ perl t2.pl 1111111111匹配 0 次或一次 b字符串[oracle@oadb test]$ cat t2.pl my $str='1a';if ($str =~ /[b]+/){print "1111111111\n"};[oracle@oadb test]$ perl t2.pl [oracle@oadb test]$ + 匹配 1 次或多次b[oracle@oadb test]$ cat t2.pl my $str='b1a';if ($str =~ /[b]+/){print "1111111111\n"};[oracle@oadb test]$ perl t2.pl 1111111111[oracle@oadb test]$ cat t1.pl my $sql="where `lc`.`tb`.`xx` = 1 and `tb2` . `id2` = 2 or `id3` > 3 and `id4` >22"; print "\$sql is $sql\n"; foreach  ($sql =~ /(`\w+`\s*\.?\s*)/g){    print "\$_ is $_\n";    push (@str,$_);    };   $sql="";   foreach (@str){     $sql=$sql.$_;    };   $sql =~ s/\s+\.\s+/\./g;   my @arr=split (/\s+/,$sql);   foreach (@arr){    print "\$_ is $_\n";   };[oracle@oadb test]$ perl t1.pl $sql is where `lc`.`tb`.`xx` = 1 and `tb2` . `id2` = 2 or `id3` > 3 and `id4` >22$_ is `lc`.$_ is `tb`.$_ is `xx` $_ is `tb2` . $_ is `id2` $_ is `id3` $_ is `id4` $_ is `lc`.`tb`.`xx`$_ is `tb2`.`id2`$_ is `id3`$_ is `id4/g模式匹配修饰符查找所有可能的匹配