Shell Programming and Scripting

20010101.txt 20010106.txt 20010111.txt 
20010116.txt 20010121.txt 20010126.txt
20010131.txt 20010205.txt 20010210.txt
20010215.txt 20010220.txt 20010225.txt
20010302.txt 20010307.txt 20010312.txt
20010317.txt 20010322.txt 20010327.txt
...20011227.txt
each file contains 1-column data which I need to paste together to make a 6-column file

paste 20010101.txt 20010106.txt 20010111.txt 20010116.txt 20010121.txt 20010126.txt > 200101.txt

paste 20010131.txt 20010205.txt 20010210.txt 20010215.txt 20010220.txt 20010225.txt > 200102.txt

and so on...

ls *txt | xargs -n6 paste

1>Write all the file names into a text file
ls *txt > temp
2>Execute this command to see what you really desired to see
perl -lne '{if($.%6==0){$x++;push(@array,$_);print "paste @array > 2001$x.txt";$#array=-1}else {push(@array,$_);}} END{$x++;print "paste @array >2001$x.txt";}' temp

3>Finally execute this command once you are ok with the output you have seen in 2nd step
perl -lne '{if($.%6==0){$x++;push(@array,$_);print "paste @array >  2001$x.txt";$#array=-1}else {push(@array,$_);}} END{$x++;print "paste  @array >2001$x.txt";}' temp | sh