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Combine 2 files by rows

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# 1  
Old 06-11-2012
Question Combine 2 files by rows
Hi,
I have 2 files, each files contain about 1 millions lines and I want to joint them to build the new files which contain each 2 lines of file1 and 1 lines of file2.
Newfiles:
line1-file1
line2-file1
line1-file2
line3-file1
line4-file1
line2-file2
.....

Could someone help me?SmilieSmilieSmilieSmilie
# 2  
Old 06-11-2012
Code:
exec 3< "$file1"
exec 4< "$file2"

while :
do
  {
    read a || break
    read b || break
  } <&3
  read c <&4  || break

  printf "%s\n" "$a" "$b" "$c"

done

# 3  
Old 06-11-2012
Nice solution cfajohnson, however will truncate output if number of records in file1 is not exactly twice number in file2.

This slight change should cater for this, but the solution isn't quite so pretty:

Code:
exec 3< "file1"
exec 4< "file2"
while [ -z "$F1" ] || [ -z "$F2" ]
do
  [ -z "$F1" ] && {
    read a && printf "%s\n" "$a"
    read a && printf "%s\n" "$a" || F1=1
  } <&3
  [ -z "$F2" ] && read b <&4 && printf "%s\n" "$b" || F2=1
done

Last edited by Chubler_XL; 06-11-2012 at 09:10 PM..
# 4  
Old 06-12-2012
Quote:
Originally Posted by Chubler_XL
Nice solution cfajohnson, however will truncate output if number of records in file1 is not exactly twice number in file2.
[/code]

If that is the case, then the requirement cannot be met as posted and requires further specification.
# 5  
Old 06-12-2012
How about:
Code:
while read a
      read b
      read c <&3
do    
  printf "%s\n" "$a" "$b" "$c"
done < file1 3<file

Or truncated:
Code:
while read a &&
      read b &&
      read c <&3
do    
  printf "%s\n" "$a" "$b" "$c"
done < file1 3<file

Last edited by Scrutinizer; 06-12-2012 at 04:25 PM..
# 6  
Old 06-12-2012
awk:
Code:
awk '1; !(NR%2) && getline<f' f=file2 file1

# 7  
Old 06-12-2012
For the shell scripts, I would suggest setting IFS to an empty string and using read's -r option, so that lines with leading/trailing whitespace and a trailing backslash are not modified.

Regards,
Alister

---------- Post updated at 04:22 PM ---------- Previous update was at 04:15 PM ----------

A paste solution:
Code:
paste -d '\n' - - file2 < file1

Regards,
Alister
These 2 Users Gave Thanks to alister For This Post:
Chubler_XL Scrutinizer
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