grep for a line then return lines above - UNIX for Dummies Questions & Answers

kingdbag · #1 03-05-2007

Hey guys,

I just want to grep for a line then return a few lines above it I can't seem to find what im looking for on google can someone help me out?

This is on Solaris 9.....

I don't have GNU grep so -B and -A commands will not work

zazzybob · #2 03-05-2007

Grab GNU grep from sunfreeware.com

http://www.sunfreeware.com/programlistsparc9.html#grep

You can try something like this although it's convoluted.

Cheers
ZB

kingdbag · #3 03-05-2007

Wow, do i really need to script something for grep to do this?

I found this and its supposed to return the above 3 lines when it finds FORWARD in the text file and it is blank...

sed -n '/FORWARD/{g;3!p;};h' crap.txt

cfajohnson · #4 03-05-2007

Quote:

Originally Posted by kingdbag

Hey guys,

I just want to grep for a line then return a few lines above it I can't seem to find what im looking for on google can someone help me out?

This is on Solaris 9.....

I don't have GNU grep so -B and -A commands will not work

Code:

pattern=$1
num=$2
shift
nawk -v pattern="$pattern" -v num="$num" '
                       { x[NR % num] = $0 }
  index( $0, pattern ) {
                 n = NR % num
                 top = n + num
                 while ( n++ < top ) print x[n % num]
               }'

I have used nawk, since the default Solaris awk is a version which has been obsolete for almost 20 years.
More recent versions on Solaris, include nawk and /usr/xpg4/bin/awk.

The above version only handles strings, not regular expressions. The following one deals with regexps, but will duplicate lines if there is an overlap. (I may fix that if I have a moment or to, or perhaps someone else can do it.)

Code:

pattern=$1
num=$2
shift
nawk -v num=$num '
                       { x[NR % num] = $0 }
  /'"$pattern"'/ {
                 n = NR % num
                 top = n + num
                 while ( n++ < top ) print x[n % num]
               }'

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
problem in the return of grep	mail2sant	Shell Programming and Scripting	1	04-11-2008 04:00 AM
return the previous line	user_prady	Shell Programming and Scripting	12	12-18-2007 04:37 AM
using Lynx and Grep to return search page rank - help	roninuta	UNIX for Dummies Questions & Answers	0	09-18-2007 09:27 AM
how to get return code in one line	bluemoon1	Shell Programming and Scripting	6	09-13-2007 07:09 PM
modifying grep to return latest files	ragha81	Shell Programming and Scripting	4	12-28-2006 01:09 PM

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode