取關鍵字下第2行

open( A, "<", "abc" ) || die "$!\n";
  @count=();
  while (<A>){
      $num++;
      if ($_ =~ /error/i)
         {$b=$num;
          print "\$b is $b\n";
          open( B, "<", "abc" ) || die "$!\n";
          while (<B>){
          print "\$. is $.\n";
          if ($. == $b + 1){print "\$_ is $_\n"};
             }
          #close B;
           };
     };
	 
Vsftp:/root# cat -n abc
     1	1
     2	2
     3	3aA
     4	313
     5	error
     6	4234
     7	12341
     8	ERROR
     9	666
    10	sdaad
    11	error
    12	313
    13	3131
	 
Vsftp:/root# perl a2.pl 
$b is 5
$. is 1
$. is 2
$. is 3
$. is 4
$. is 5
$. is 6
$_ is 4234

$. is 7
$. is 8
$. is 9
$. is 10
$. is 11
$. is 12
$. is 13
$b is 8
$. is 14
$. is 15
$. is 16
$. is 17
$. is 18
$. is 19
$. is 20
$. is 21
$. is 22
$. is 23
$. is 24
$. is 25
$. is 26
$b is 11
$. is 27
$. is 28
$. is 29
$. is 30
$. is 31
$. is 32
$. is 33
$. is 34
$. is 35
$. is 36
$. is 37
$. is 38
$. is 39

文件句柄不關閉,會讀完後繼續讀

關閉文件句柄後


Vsftp:/root# cat abc
1
2
3aA
313
error
4234
12341
ERROR
666
sdaad
error
313
3131
Vsftp:/root# perl a2.pl 
$_ is 12341

$_ is sdaad

$_ is 3131

Vsftp:/root# cat a2.pl 
open( A, "<", "abc" ) || die "$!\n";
  @count=();
  while (<A>){
      $num++;
      if ($_ =~ /error/i)
         {$b=$num;
          open( B, "<", "abc" ) || die "$!\n";
          while (<B>){
          if ($. == $b + 2){print "\$_ is $_\n";close B;last;};
             }
           };
     };