New Trick Learned

Learned a new trick from the Shell Programming and Scripting from Unix and Linux Forum. Suppose you need to convert a single column file to multi-column with colon(:) as separator

$ cat a
one
two
three
four
five
six
seven
eight
nine
ten
eleven
twelve

$ cat a | paste -d: - - -
one:two:three
four:five:six
seven:eight:nine
ten:eleven:twelve

$ cat a | paste -d: - - - -
one:two:three:four
five:six:seven:eight
nine:ten:eleven:twelve

$ cat a | paste -d: - - - - - -
one:two:three:four:five:six
seven:eight:nine:ten:eleven:twelve

In Unix, if "-" is specify as the file input, it will take the input from the pipe. In our case, multiple "-" in the paste will consume input one line at a time. Just a recap, I blogged about paste command in Solaris has a limit of no more than 12 files

$ (cat a a a) | paste -d: - - - - - - - - - -
one:two:three:four:five:six:seven:eight:nine:ten
eleven:twelve:one:two:three:four:five:six:seven:eight
nine:ten:eleven:twelve:one:two:three:four:five:six
seven:eight:nine:ten:eleven:twelve::::

$ (cat a a a) | paste -d: - - - - - - - - - - - -
one:two:three:four:five:six:seven:eight:nine:ten:eleven:twelve
one:two:three:four:five:six:seven:eight:nine:ten:eleven:twelve
one:two:three:four:five:six:seven:eight:nine:ten:eleven:twelve

$ (cat a a a) | paste -d: - - - - - - - - - - - - - -
paste: too many files- limit 12