Select last block from a file

misenkiser · #1 (**permalink**) 10-11-2006

Hi,

I have to always select last portion of a block identified by 2 fixed keywords
which repeats in a file for eg

START
....
...
END

START
....
...
END

START
....
...
END

THE LAST PORTION WITHIN (START AND END) SHOULD ALWAYS BE SELECTED

ghostdog74 · #2 (**permalink**) 10-11-2006

python alternative:
INput:
START
1st
END

START second block
second
END

START third block
last
END

Code:

store =[]
data = open("input").readlines() #each file into array
for i in data[::-1]: #starting from last entry, work backwards
        i = i.strip() #strip leading/trailing spaces
 	if i.startswith("END"):continue
 	elif i.startswith("START"):break
 	else: store.append(i) 
print ''.join(store[::-1]) #reverse result back..

output:

Code:

last

shreedhar · #3 (**permalink**) 10-11-2006

#! /usr/bin/perl

$file='last_block'; #file name
open (FH, $file);

while ($line=<FH>) {
undef(@array);
chomp($line);
if($line =~ /^START/) {
while ($temp = <FH>) {
chomp($temp);
if ($temp =~ /^END/) {
last;
}
push(@array, $temp);
}
@copy=@array;
}
}
print "@copy\n";

input file (last_block):
START
i am in first block
Now tell me i am...
END

START
i am in second block
now tell me i am
...
END

START
I am last block
did u asked me
END

output:
I am last block did u asked me

yashavant.a · #4 (**permalink**) 10-11-2006

#!/bin/bash
file=input
line_no=1

total=`cat $file | wc -l`
state=0

while [ $line_no -le $total ]
do
line=`tail -$line_no $file | head -1`

if [ "$line" = "END" ]
then
state=1
elif [ "$line" = "START" ]
then
break
elif [ $state -eq 1 ]
then
output=$line"\n"$output
fi

line_no=`expr $line_no + 1`
done

echo -e $output

mahendramahendr · #5 (**permalink**) 10-11-2006

$ more test.pl
#!/usr/bin/perl -w

$file="test.txt";

open(FH,$file) || die "Unable to open $file : $!\n";

my $line;
my $strt_str=0;
my @arr=();

while ( $line = <FH> )
{
chomp $line;

if( $line =~ /^START/ ) {
@arr = ();
$strt_str = 1;
}

push(@arr,$line) if( $strt_str == 1 );

$strt_str = 0 if ( $line =~ /^END/ );
}

print join("\n",@arr)."\n";

$ more test.txt
START
i am in first block
Now tell me i am...
END

START
i am in second block
now tell me i am
...
END

START
I am last block
did u asked me
END

$ perl test.pl
START
I am last block
did u asked me
END

misenkiser · #6 (**permalink**) 10-11-2006

the keywords START and END
are not the only words in the line so the code fails

START .........................
.....
.....
.....
......
END ............................

I only know that the keywords wil be START and END but there can be other chars in the line

aigles · #7 (**permalink**) 10-11-2006

Another way using awk:

Code:

awk '
     /^START/ { inside = 1 ; count = 0; next}
     /^END/   { inside = 0 ;next}
     inside  { line[count++] = $0 }
     END     { for (i=1; i<=count; i++) print line[i] }
    ' input_file

Jean-Pierre

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