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Full Discussion: how to sed with tail
Top Forums UNIX for Dummies Questions & Answers how to sed with tail Post 82249 by zazzybob on Tuesday 30th of August 2005 05:27:01 AM
Old 08-30-2005
Using the shell, i'd do something convoluted like this
Code:
$ cat ./redlotus.sh
#!/bin/ksh

matchfile="redlotus.txt"

matches=`echo "${line}" | egrep -in "Error|Exception" ${matchfile}`
echo "${matches} " | while read line; do
   lineno=`echo "${line}" | cut -d: -f1`
   match=`echo "${line}" | cut -d: -f2`
   echo "Match found - line ${lineno} - ${match}"
   minline=$(( lineno - 5 ))
   [[ "$(( lineno - 5 ))" -lt 1 ]] && minline=1
   sed -n "$minline,$(( lineno - 1 ))p" ${matchfile}
   sed -n "$lineno p" ${matchfile}
   sed -n "$(( lineno + 1 )),$(( lineno + 5 ))p" ${matchfile}

   # note we could just do
   # sed -n "$minline, $((lineno + 5))p" ${matchfile}
   # but i've left this as-is to show you how to grab the previous, and the
   # next, five lines....
done
exit 0

No doubt, there is a far easier way (using -C option to GNU (e)grep for example)....

Cheers
ZB
 

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OPENPAM_READLINE(3)					   BSD Library Functions Manual 				       OPENPAM_READLINE(3)

NAME
openpam_readline -- read a line from a file LIBRARY
Pluggable Authentication Module Library (libpam, -lpam) SYNOPSIS
#include <sys/types.h> #include <security/pam_appl.h> #include <security/openpam.h> char * openpam_readline(FILE *f, int *lineno, size_t *lenp); DESCRIPTION
The openpam_readline function reads a line from a file, and returns it in a NUL-terminated buffer allocated with malloc(3). The openpam_readline function performs a certain amount of processing on the data it reads. Comments (introduced by a hash sign) are stripped, as is leading and trailing whitespace. Any amount of linear whitespace is collapsed to a single space. Blank lines are ignored. If a line ends in a backslash, the backslash is stripped and the next line is appended. If lineno is not NULL, the integer variable it points to is incremented every time a newline character is read. If lenp is not NULL, the length of the line (not including the terminating NUL character) is stored in the variable it points to. The caller is responsible for releasing the returned buffer by passing it to free(3). RETURN VALUES
The openpam_readline function returns NULL on failure. SEE ALSO
free(3), malloc(3), pam(3) STANDARDS
The openpam_readline function is an OpenPAM extension. AUTHORS
The openpam_readline function and this manual page were developed for the FreeBSD Project by ThinkSec AS and Network Associates Laboratories, the Security Research Division of Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 (``CBOSS''), as part of the DARPA CHATS research program. BSD
December 21, 2007 BSD
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