Dr.Dimitri Vulis KOTM wrote:
ichudov@algebra.com (Igor Chudov @ home) writes:
Dr.Dimitri Vulis KOTM wrote:
Here's a neat trick: if you want to list a file with line numbers, try:
grep -n "^" file
cat -n works faster.
Did you time it?
Yes, I wrote a prog that quickly prints a specified number of lines (see below). Then I piped the output of that program to cat -n and grep, respectively, and here's what I got: manifold::~/tmp==>./a.out 1000000 | /usr/bin/time cat -n > /dev/null 1.32user 0.05system 0:01.62elapsed 84%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (46major+17minor)pagefaults 0swaps manifold::~/tmp==>./a.out 1000000 | /usr/bin/time grep -n '^' > /dev/null 19.75user 0.04system 0:20.71elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (88major+26minor)pagefaults 0swaps The difference is about fifteen times. - Igor. #include <stdio.h> main( int argc, char *argv[] ) { int n = atoi( argv[1] ); for( ; n; n-- ) putchar( '\n' ); }