On 1/30/2016 1:03 AM, Christian Gollwitzer wrote:
Am 30.01.16 um 05:58 schrieb Random832:
On Fri, Jan 29, 2016, at 23:46, Hongyi Zhao wrote:
awk '{a[NR]=$0} END {while (NR) print a[NR--]}' input_file
perl -e 'print reverse<>' input_file
Well, both of those read the whole file into memory - tac is sometimes
smarter than that, but that makes for a more complex program.
Now I'm curious. How is it possible to output the first line as last
again if not by remembering it from the every beginning? How could tac
be implemented other than sucking up everything into memory?
One could read the file by lines and make a list of start-of-line
positions. Reverse the list. Read each line. Details omitted.
--
Terry Jan Reedy
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