tdt-cat-yesterday-multilogs

#! /bin/sh

# Cat all log lines from yesterday from a multilog directory. It assumes that the dtm of
# the log files are as they where when they were created and that the contents are created
# by multilog and thus amenable to date decoding with tai64nlocal.
#
# Typically usage is to feed the output into a log analysis program such as
# tdt-analyze-proxylog or tdt-analyze-serverlog. E.g.:
#
# tdt-cat-yesterday-multilogs /var/log/trustydns-proxy | tdt-analyze-proxylog

set -e
cd ${1:-.} # cd to dir on command line if given

######################################################################
# Work out when yesterday was. There's the easy way and the hard way. The hard way involves setting
# the unix time value back by 1/3 of a day until the day of month changes. We can't just go back
# 86400 seconds because today or yesterday may have been a short day due to daylight savings. Nor
# can we just subtract a small amount as we don't know how far thru today we are.
######################################################################

yesterday=""

case `uname`
in
    Darwin|FreeBSD)
	yesterday=`date -v -1d +%Y-%m-%d`
	;;
    Linux) # work our way backwards as a local day can be shorter than 86400 seconds
	now=`date +%s`
	nowDD=`date --date=@${now} +%d`
	try=$now
	for dec in 28800 43200 86400 115200
	do
	    try=`expr $now - ${dec}`
	    tryDD=`date --date=@${try} +%d`
	    if [ $tryDD -ne $nowDD ];
	    then
		yesterday=`date --date=@${try} +%Y-%m-%d`
		break
	    fi
	done
	;;
    *)
	echo Warning: Guessing at how to determine yesterday for platform: `uname` >&2
	yesterday=`date -v -1d +%Y-%m-%d` # Maybe this will work, maybe it won't
	;;
esac

if [ -z "${yesterday}" ]; then
    echo Warning: Could not determine the date of yesterday. Cannot continue.... >&2
    exit 1
fi

# Search for files that have been modified in the last 2 days. That will ensure we get a complete
# set of log entries to greap against.

find . -mtime -2 -type f | sort | xargs cat | tai64nlocal | grep ^${yesterday}