extract block of text

[mike]

hi
i have some data contained in a file like this:

/* ----------------- Heading1 ----------------- */

line: Heading1 type: b
#owner: (e-mail address removed)


/* ----------------- Heading2 ----------------- */

line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server


/* ----------------- Heading3 ----------------- */

.....


how can i extract the data from "Heading2" to "Heading3" such that
i have this output without the "Headings" and without the empty lines.

line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server

thanks for any help

 

[peter pilsl]

how can i extract the data from "Heading2" to "Heading3" such that
i have this output without the "Headings" and without the empty lines.

line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server

thanks for any help

even if OT, cause no perl-question included:

standard approach:
you read the input line per line. If you reach Heading2, set a flag. If you
reach Heading3 clear the flag. For each line that is not empty check if the
flag is set - if yes print out the line. (its more efficient to check the
flag first and then if the line is empty)

if the inputfile is known to be of limited length, you can read all the
file at once by altering the $/-variable and use the m//-operator to get
the Text between Heading2 and Heading3 and the s///-operator to eliminate
empty lines.

If you have any questions regarding one of these steps please feel free to
ask again and dont forget to post part of your source so we can help you
even better.

best,
peter

 

[Tad McClellan]

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^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^


I'll add that to my scorefile. Thanks.

The following Code should handle your task


open(filein,"<file")

That has a syntax error.

You should use UPPER CASE filehandles.

You should always, yes *always*, check the return value from open():

open(FILEIN, 'file') or die "could not open 'file' $!";

 

[Tad McClellan]

how can i extract the data from "Heading2" to "Heading3" such that
i have this output without the "Headings" and without the empty lines.

--------------------------------------------------------------------------
#!/usr/bin/perl
use strict;
use warnings;

my $record = '';
while ( <DATA> ) {
if ( m#/\* ----------------- Heading\d+ ----------------- \*/# ) {
$record =~ s/^\s+//;
$record =~ s/\s+$//;
print "$record\n-----\n";
$record = ''; # clear buffer
}
else {
$record .= $_;
}
}

# final record
$record =~ s/^\s+//;
$record =~ s/\s+$//;
print "$record\n-----\n";

__DATA__
/* ----------------- Heading1 ----------------- */

line: Heading1 type: b
#owner: (e-mail address removed)


/* ----------------- Heading2 ----------------- */

line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server


/* ----------------- Heading3 ----------------- */

.....

 

[Ben Morrow]

i have some data contained in a file like this:

/* ----------------- Heading2 ----------------- */

line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server


/* ----------------- Heading3 ----------------- */

how can i extract the data from "Heading2" to "Heading3"

[without the blank lines]

<untested>

perl -ne'next if /^\s*$/; print if m|/* -+ Heading2| .. m|/* -+ Heading3|'

Ben

 

[Sara]

**** Post for FREE via your newsreader at post.usenet.com ****

The following Code should handle your task


open(filein,"<file")

while ($line=<filein>) {

if ( $line =~ m/\/\* -+ Heading2 -+ \*\/ ) { $flag=0 };

if ( $flag == "1" && ! ( $line =~ m/^$/ )) {
print $line;
}

if ( $line =~ m/\/\* -+ Heading1 -+ \*\/ ) { $flag=1 };
}


christoph



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Bleech- if you're looping through this data line by line you might as
well use Basic or Fortran.. and if you INSIST on looping at least
slurp the file into an array with my @f = <F> , close the file, then
loop over the array (its debuggable for one thing).

But hey let's use the power of Perl as long we we're using Perl? I'm
not going to solve your entire problem but here is a nice approach
(with no looping) and it has a much more useful output should your
requirements change later (as they often do in the real world) (don;t
ya hate parenthetical expressions?):

#!/usr/bin/perl -wd

$_ =
'/* ----------------- Heading1 ----------------- */

line: Heading1 type: b
#owner: (e-mail address removed)


/* ----------------- Heading2 ----------------- */

line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server


/* ----------------- Heading3 ----------------- */


line: Heading3 type: x
command: echo "hi"
owner: (e-mail address removed)
machine: server

';

@a = split /\n*\/\*\s*\-+\s*Heading(\d+)[^\n]+\n\n*/;
shift @a unless $a[0]; # toss off empty element
my %a = @a;

print "done\n";

*************************************************************************

The neat part is you have what you wanted (cleaned up blocks), but
stored in a HASH with a hashkey that is the header number, voila!


DB<1> x %a
0 1
1 'line: Heading1 type: b
#owner: (e-mail address removed)'
2 3
3 'line: Heading3 type: x
command: echo "hi"
owner: (e-mail address removed)
machine: server

'
4 2
5 'line: Heading2 type: c
command: echo "hi"
owner: (e-mail address removed)
machine: server'


So now you can do whatever you like with the blocks, and in fact the
whole program was really like 3 lines, no loops, very easily debugged
and changed.

G

 

[Tore Aursand]

while ($line=<filein>) {
[...]

Bleech- if you're looping through this data line by line you might as
well use Basic or Fortran..

There are times when it's a wise thing to loop through data.

 

[Dave Weaver]

<untested>

perl -ne'next if /^\s*$/; print if m|/* -+ Heading2| .. m|/* -+ Heading3|'

ITYM:

perl -ne'next if /^\s*$/; print if m|/\* -+ Heading2| .. m|/\* -+ Heading3|'

<also untested>

Dave.

 

[Sara]

while ($line=<filein>) {
[...]

Bleech- if you're looping through this data line by line you might as
well use Basic or Fortran..

There are times when it's a wise thing to loop through data.

Yes, and this doesn't appear to be one of those times..

 

[Anno Siegel]

while ($line=<filein>) {
[...]

Bleech- if you're looping through this data line by line you might as
well use Basic or Fortran..

There are times when it's a wise thing to loop through data.

Yes, and this doesn't appear to be one of those times..

How would you know?

The main reason *for* file slurping is non-sequential access to parts of
the file. Picking out some matches can be done sequentially, you don't
*need* the file content in memory for that.

The main reason *against* file slurping is large file size (current or
expected). We know nothing about that.

The only reason for file slurping in this situation would be laziness.
That doesn't rule it out as a good solution, but it doesn't make it
the method of choice.

Anno

 

[mike]

ITYM:

perl -ne'next if /^\s*$/; print if m|/\* -+ Heading2| .. m|/\* -+ Heading3|'

<also untested>

Dave.

Thanks everyone for the tips that you have given

I went back to try out this piece instead

while($line=<FILE>)
{
chomp($line);
if ( $line =~ m/\/\* -+ $search*/ ) {
while ( $nextline = <FILE>)
{
if ( $nextline =~ m|\/\* -+| )
{
last;
}
print "$nextline" ;
}
}

i think it works ok (please correct me if i am wrong thanks ... but
i read from perl docs that "last" exits the current
so was wondering is it necessary to put a "last" just before ending
the outer
while...


while($line=<FILE>)
{
chomp($line);
if ( $line =~ m/\/\* -+ $search*/ ) {
while ( $nextline = <FILE>)
{
if ( $nextline =~ m|\/\* -+| )
{
last;
}
print "$nextline" ;
}
last;
}

 

[Anno Siegel]

Thanks everyone for the tips that you have given

I went back to try out this piece instead

while($line=<FILE>)
{
chomp($line);
if ( $line =~ m/\/\* -+ $search*/ ) {
while ( $nextline = <FILE>)
{
if ( $nextline =~ m|\/\* -+| )
{
last;
}
print "$nextline" ;
}
}

i think it works ok (please correct me if i am wrong thanks ... but
i read from perl docs that "last" exits the current
so was wondering is it necessary to put a "last" just before ending
the outer
while...


while($line=<FILE>)
{
chomp($line);
if ( $line =~ m/\/\* -+ $search*/ ) {
while ( $nextline = <FILE>)
{
if ( $nextline =~ m|\/\* -+| )
{
last;
}
print "$nextline" ;
}
last;
}

That would unconditionally end the outer loop after the first round,
certainly not what you want.

The way the program was given, it continues to search after each match.
If you only want the first match, label the outer loop (see perldoc -f
last):

LOOP: while($line=<FILE>)
{
chomp($line);
if ( $line =~ m/\/\* -+ $search*/ ) {
while ( $nextline = <FILE>)
{
if ( $nextline =~ m|\/\* -+| )
{
last LOOP;
}
print "$nextline" ;
}
}

Anno