UNIX for Dummies Questions & Answers

Hi all, looking for some help here. I'm what you'd call a dirty programmer. my shell scripts might be ugly, but they (usually) function...

Say I have a single column text file with a list of dates (yyyymmdd) that represent the elevation of a point on that date (I work with land subsidence, so the elevation changes thru time):

Code:

date1
date2
date3
date4
...
date-n

I want to then create another two column text file that contains a list of all possible date combinations, so I can then figure out the change in elevation between two time periods. I need to create this text file for input into another software I use.

Code:

date1  date2
date1  date3
...
date1  date-n
date2  date3
date2  date4
...
date2  date-n
date3  date4
...
date-n-1 date-n

Any ideas?

Thanks all!
JB

Try (for seven dates):

Code:

awk '{T[NR]=$1} END {for (i=1; i<NR; i++) {for (j=i+1; j<=NR; j++) print T[i], T[j]}}' file
date1 date2
date1 date3
date1 date4
date1 date5
date1 date6
date1 date7
date2 date3
date2 date4
date2 date5
date2 date6
date2 date7
date3 date4
date3 date5
date3 date6
date3 date7
date4 date5
date4 date6
date4 date7
date5 date6
date5 date7
date6 date7

perfect, thanks!!!!