Shell Programming and Scripting

 grep -B 10 ¨pattern¨ file

#!/bin/ksh
Usage() {
 echo " mygrep pat files.."
 exit
}

(( $# < 2 )) && Usage

Leading=10

PAT=$1
shift;
FileList=$@

for FileName in ${FileList} ; do
  for LineNo in $( grep -n  $PAT $FileName | cut -d":" -f1 )  ; do
     From=$((LineNo-Leading+1))
     sed -n "$From,$LineNo"p $FileName
  done
done

#!/bin/bash -

# @(#) s3       Demonstrate printing of text before a matched line.

echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version =o $(_eat $0 $1)

P=./pvg

echo
echo " Input file data3:"
cat data3

echo
echo " Looking for d, normal search:"
$P d data3

echo
echo " Looking for d, print previous 2:"
$P -B 2 d data3

echo
echo " Looking for d, print previous 2, separator:"
$P -s '     ----- \n' -B 2 d data3

echo
echo " Looking for ask, print previous 100, quiet:"
$P -q -B 100 ask data3

exit 0

% ./s3
(Versions displayed with local utility "version")
Linux 2.6.11-x1
GNU bash 2.05b.0

 Input file data3:
     1  Alabama AL
     2  Alaska AK
     3  Arizona AZ
     4  Arkansas AR
     5  California CA
     6  Colorado CO
     7  Connecticut CT
     8  Delaware DE
     9  District of Columbia DC
    10  Florida FL

 Looking for d, normal search:
     6  Colorado CO
    10  Florida FL
 ( Lines read: 10; hits: 2 )

 Looking for d, print previous 2:
     4  Arkansas AR
     5  California CA
     6  Colorado CO
     8  Delaware DE
     9  District of Columbia DC
    10  Florida FL
 ( Lines read: 10; hits: 2 )

 Looking for d, print previous 2, separator:
     4  Arkansas AR
     5  California CA
     6  Colorado CO
     -----
     8  Delaware DE
     9  District of Columbia DC
    10  Florida FL
 ( Lines read: 10; hits: 2 )

 Looking for ask, print previous 100, quiet:
     1  Alabama AL
     2  Alaska AK