I have a HTML list of about 500 items and a "filter" box above it. I started by using jQuery to filter the list when I typed a letter (timing code added later): $('#filter').keyup( function() { var jqStart = (new Date).getTime(); var search = $(this).val().toLowerCase(); var $list = $('ul.ablist > li'); $list.each( function() { if ( $(this).text().toLowerCase().indexOf(search) === -1 ) $(this).hide(); else $(this).show(); } ); console.log('Time: ' + ((new Date).getTime() - jqStart)); } ); However, there was a couple of seconds delay after typing each letter (particularly the first letter). So I thought it may be slightly quicker if I used plain Javascript (I read recently that jQuery's each function is particularly slow). Here's my JS equivalent: document.getElementById('filter').addEventListener( 'keyup', function () { var jsStart = (new Date).getTime()...
For GNU grep you can use -B num to set how many lines before the match and -A num for the number of lines after the match.
ReplyDeletegrep -B 3 -A 2 foo README.txt
If you want the same amount of lines before and after you can use -C num.
grep -C 3 foo README.txt
This will show 3 lines before and 3 lines after.
-A and -B will work, as will -C n (for n lines of context), or just -n (for n lines of context).
ReplyDeleteAck works with similar arguments than grep, and accept -C. But it's usually better for searching through code.
ReplyDeleteI normally use
ReplyDeletegrep searchstring file -C n # n for number of lines of context up and down
Many of the tools like grep also have really great man files too. I find myself referring to grep's man page a lot because there is so much you can do with it.
man grep
Many GNU tools also have an info page that may have more useful information in addition to the man page.
info grep
Ok, but what if want to show all lines of output after the match? grep -A0 and grep -A-1 don't cut it... – Noah Jul 22 at 2:18
ReplyDeleteawk can do this:
awk '/search_pattern/,0' filename
grep astring myfile -A 5 -B 5
ReplyDeleteThat will grep "myfile" for "astring", and show 5 lines before and after each match
I keep a copy of Brendan Gregg's perl script around for this purpose. Works well.
ReplyDelete