tools: add small tool for debug log analysis

tests/debug_extract.sh

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+#!/bin/bash
+# This is primarily a tool to extract relevant parts of large debug
+# files
+# usage:
+# $1 - file to search
+# $2 - search term
+# $3 - number of lines before first match (optional, default 5000)
+# $4 - number of lines after first match (optional, default 10000)
+# output is directed to stdout - use redirection if desired
+#
+# Copyright (C) 2018 by Rainer Gerhards, released under ASL 2.0
+
+if [ "$1" == "" ]; then
+	echo file name must be given
+	exit 1
+fi
+if [ "$2" == "" ]; then
+	echo search term must be given
+	exit 1
+fi
+FILE="$1"
+SEARCH_TERM="$2"
+if [ "$3" == "" ]; then
+	LINES_BEFORE=5000
+else
+	LINES_BEFORE="$3"
+fi
+if [ "$4" == "" ]; then
+	LINES_AFTER=5000
+else
+	LINES_AFTER="$4"
+fi
+line=$(cat -n $FILE | grep "$SEARCH_TERM" |cut -f1 |head -1)
+if [ "$line" == "" ]; then
+	echo search term not found!
+	exit 1
+fi
+startline=$((line-LINES_BEFORE))
+numlines=$((LINES_AFTER + LINES_BEFORE+1)) # +1 for search term line itself!
+printf "file %s lines %d to %d, arround first occurence of '%s':\n" \
+	$FILE $startline $((startline+numlines)) $SEARCH_TERM
+tail -n +$startline $FILE | head -n $numlines