merlyn@iwarp.intel.com (Randal Schwartz) (06/14/90)
In article <1990Jun13.181047.12420@athena.mit.edu>, lfk@E40-008-8 (Lee F Kolakowski) writes: | On 13 Jun 90 17:26:27 GMT, | stevep@dgp.toronto.edu (Steve Portigal) said: | > I am looking for a simple Unix way to extract every other line of | > a text file. Can anyone help? Email please and I'll post one summary. | If you have awk or gawk it is very simple... | | Try this: | | for lines 0, 2, 4, ..... | | gawk ' | { | if (!(NR % 2) { | print $0 | } | }' | | for lines 1, 3, 5, ... | | gawk ' | { | if (NR % 2) { | print $0 | } | }' | | These scripts are very simple. They use the built-in variable NR | (record number) to count lines. If the number of lines modulo 2 | equals zero the expression (!(NR % 2)) is true and the line will be | printed. and of course, in Perl, it'd be: perl -ne 'print if $. % 2' for the odd lines (even if you count beginning at zero :-), and: perl -ne 'print unless $. % 2' for the even lines (odd if you count beginning at zero :-). [note to Perl fanatics... requires 3.18] Just another Perl hacker, -- /=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\ | on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III | | merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn | \=Cute Quote: "Welcome to Portland, Oregon, home of the California Raisins!"=/
tneff@bfmny0.BFM.COM (Tom Neff) (06/14/90)
Aw come on, Tom and Randal. perl -ne 'print if $. % 2;' is for poofters! Real men use perl -pe '$_ = <>;' :-) -- The real problem with SDI is %/ Tom Neff that it doesn't kill anybody. /% tneff@bfmny0.BFM.COM