UNIX for Beginners Questions & Answers

]I would like to make the second file label 'b' print down the first file label 'a', like shifting down the file creating new lines I want it to print all the way down until the first line of the second file hit the last line of the first file. Would I have to put this into a file itself or could I do it from the terminal?

What it does now:


paste -d ' ' a b

Code:

1           a 
  2         b
  3         c
  4         d 
  5         e
  6         
  7         
  8        
  9

Desired output:

1 ↓
2 a
3 b
4 c
5 d
6 e
7
8
9



1
2
3 ↓
4 a
5 b
6 c
7 d
8 e
9


Re-looping
1 b
2 c
3 d
4 e
5
6
7 ↓
8 List is about to loop
9 a

One way:

Code:

#!/bin/bash

# Create temporary file to hold newlines
touch /tmp/$$

# Open both files to read line-by-line
exec 5<file1
exec 6<file2

# Read lines from both until file2 runs out
while read LINE <&6 && read LINE <&5
do
        :
done

# Run loop same number of times as lines left in file1.
while read LINE <&5
do
        cat /tmp/$$ file2 | paste file1 /dev/stdin
        echo >> /tmp/$$
        echo
done

cat /tmp/$$ file2 | paste file1 /dev/stdin


rm -f /tmp/$$ # Delete temporary file
# Close file descriptors
exec 5>&-
exec 6>&-

Re-looping I'm less certain of. Perhaps the files themselves should be generated at need. How large are they in a non-trivial example?

Thank you for the reply,

Re-looping mean just looping through the list again, the files are over 20gbs.

and how to take the space out between the files to merge them together?

Just following the example posted. Using files a and b to create c loop example:

Code:

awk '
NR==FNR {a[c++]=$0; next;}
{b[++d]=$0;}
END { for (i=0; i<c; i++) {
for (j=0; j<c; j++) print a[j], b[(j-i)<0?(c+j-i):(j-i)];
print _;
}
}' a b > c

Thank you for the reply,

I just want the whole second file to print through the first file. I didn't want the line to have breaks. I was just showing an example of a file completely printing through another.

And how to merge the files together instead of having a space between them?

try:

Code:

awk '
NR==FNR {a[c++]=$0; next;}
{b[++d]=$0;}
END { for (i=0; i<c; i++) {
for (j=0; j<c; j++) {
v=j-i;
if (v < 0) v=v+c;
print a[j], b[v];
}
print _;
}
}' a b > c

or gawk instead of [ICODE]awk[/ICODE

Thank you for the reply,

I had go it to work, i had to go back and re-do it.