Merging two different files with conditions

Question

I have two different files as shown below.

Content of a.txt:

HDR|1||||||||||               
DTL|@|||||||||||             
TLR|||||||||||||              
HDR|1||||||||||||            
DTL|||||||||||||              
TLR|||||||||||||     

Content of b.txt:

HDR|2||||||||||  
DTL|||||||||||||
TLR|||||||||||||
HDR|2|||||||||||| 
DTL|last||||||||||||
TLR|||||||||||||

Here I have to take out all the lines till 1st "TLR" in a.txt and b.txt and merge into 1.txt ,same way take out all the lines After 1st "TLR" in a.txt and b.txt and merge into 2.txt

output should be:

Content of 1.txt:

HDR|1|||||||||| 
DTL|@||||||||||| 
TLR|||||||||||||
HDR|2|||||||||| 
DTL|||||||||||| 
TLR|||||||||||||  

Content of 2.txt:

HDR|1|||||||||| 
DTL|||||||||||| 
TLR|||||||||||||
HDR|2|||||||||| 
DTL|last||||||||||| 
TLR|||||||||||||  

How can we accomplish this using UNIX Script?

Answer 1

One way to do it:

sed -ne '1,/^TLR/p' a.txt > 1.txt
sed -ne '1,/^TLR/p' b.txt >> 1.txt
sed -e '1,/^TLR/d' a.txt > 2.txt
sed -e '1,/^TLR/d' b.txt >> 2.txt

That is:

• Print the lines from a.txt until matching /^TLR/ and create 1.txt
• Print the lines from b.txt until matching /^TLR/ and append to 1.txt
• Drop the lines from a.txt until matching /^TLR/ and create 2.txt
• Drop the lines from b.txt until matching /^TLR/ and append to 2.txt

Answer 2

You could run the same command twice on the two different files:

$ perl -ne 'print if $a<1; $a++ if /TLR/; ' a.txt > 1.txt
$ perl -ne 'print if $a<1; $a++ if /TLR/; ' b.txt >> 1.txt

and

$ perl -ne 'print if $a>=1; $a++ if /TLR/; ' a.txt > 2.txt
$ perl -ne 'print if $a>=1; $a++ if /TLR/; ' b.txt >> 2.txt

These simple scriptlets will add 1 to the value of the variable $a if the current line contains TLR. They then check the value of $a to decide if this line should be printed or not.

You can combine both operations into one command with:

$ perl -e '
  foreach my $file(@ARGV){
    open(my $fh,"$file"); $a=0;
    while(<$fh>){
     $a<1 ? (push @{$lines{1}},$_) : (push @{$lines{2}},$_); $a++ if /TLR/}} 
  END{open(my $fh,">","1.txt"); print $fh @{$lines{1}}; 
      open(my $fh,">","2.txt"); print $fh @{$lines{2}};}' a.txt b.txt