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Re: insert line in between two lines
by holli (Abbot) on Mar 16, 2005 at 11:39 UTC
    perl -ni -e "print qq($_\n);" yourfile.name


    holli, /regexed monk/
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Re: insert line in between two lines
by prasadbabu (Prior) on Mar 16, 2005 at 11:32 UTC
    s/\n([^\n]*)/\n$newline$1/s;

    update:'\n' removed from match pattern.

    Prasad

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[d/l]
      here is what to i needed specifically
      $cwd = cwd();
      print"$cwd\n";

      i want the following
      $cwd = cwd();
      $exec = $ENV{EXEC}
      print"$cwd\n";

      i am sorry for not giving detail earlier
[reply]

        This might work for you.

        undef $/;
$a = <DATA>;
$nline =q($exec = $ENV{EXEC};);
$a =~ s/\n([^\n]+)/\n$nline\n$1/s;
print "$a";
__DATA__
$cwd = cwd();
print"$cwd\n";

        [download]

        Prasad

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Re: insert line in between two lines
by tphyahoo (Vicar) on Mar 16, 2005 at 11:50 UTC
    This sticks a newline between every line in the input file. You also get a blank line at the end, which strictly speaking, is not "between" two lines. 
    #perl linesBetween.pl linesBetweenTest.txt
#makes backup just in case
use strict;
use warnings;

my $infile = shift;

$infile =~ /(.*)(\.txt$)/ or die 'Input file must be of type .txt';

my $backupfile = "$1.bak";
my $tmpfile = "$1.tmp";
`copy $infile $1.bak`;

my $F;
my %lines;

open F, "< $infile" or die "couldn't open $infile";
open G, "> $tmpfile" or die "couldn't open $tmpfile";


while (<F>) {
    print G "$_\n";
}
close F;
close G;

`del $infile`;
`move $tmpfile $infile`;

    [download]
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Re: insert line in between two lines
by perlsen (Chaplain) on Mar 16, 2005 at 11:58 UTC 
    undef $/;
open(IN, "< 1.txt") ;
$str = <IN>;
close(IN);

$str =~ s#\n(.+?)\n#\n\$exec \= \$ENV\{EXEC\}\n$1\n#gsi;
open(OUT, "> 2.txt") ;
print OUT $str;

input:
*********
hai
this
is
the
test
input
sample


output:
**********
hai
$exec = $ENV{EXEC}
this
is
$exec = $ENV{EXEC}
the
test
$exec = $ENV{EXEC}
input
sample

    [download]
[reply]
[d/l]
      perlsen thanks, but as i told earlier that i need to add
      $exec = $ENV{EXEC}
      only once in between
      $cwd=cwd();
      and
      print"$cwd\n"; i hope you will get what i want .
[reply]

        Remove 'g' option modifier for that.

        Prasad

[reply]
Re: insert line in between two lines
by chas (Priest) on Mar 16, 2005 at 13:56 UTC
    Assuming you know the line number after which you want to add the new line (say 2; in your example it's 1), you could do something like: 
    my $linenum=2;
my $linetoadd="Something\n";
my $i;
while(<>){
 ++$i;
 if($i==$linenum) {print;print $linetoadd;}
 else {print;}
 }

    [download]
    (You can direct the output to a new file.)
    You could also arrange things so the line number and new line are given as args, depending on how this is to be used. (i.e a one time run or or a utility used frequently; of course, if it's just a one time thing, I'd simply use an editor.)
    Hope this is what you wanted.
    chas
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