ensureSyslogEntry

set -e # terminate on error

LOG_LDM=${1?LDM logging facility not set}
SYSLOG_CONF=${2?System logging configuration-file not set}
LDM_LOGFILE=${3?LDM log file pathname not set}

# Modifies a syslog-ng.conf(5) file.
#
modifySyslogNg() {
    sed "s/\(and not facility([^)]*\))/\1,$LOG_LDM)/" "$SYSLOG_CONF" \
            >"$SYSLOG_CONF".new
    cat >>"$SYSLOG_CONF".new <<EOF

# Unidata LDM:
destination d_ldm { file("$LDM_LOGFILE"); };
filter      f_ldm { facility($LOG_LDM); };
log               { source(s_sys); filter(f_ldm); destination(d_ldm); };
EOF
    cp "$SYSLOG_CONF" "$SYSLOG_CONF".old
    mv -f "$SYSLOG_CONF".new "$SYSLOG_CONF"
}

# Modifies a syslog.conf(5) or rsyslog.conf(5) file.
#
modifySyslog() {
    if fgrep $LOG_LDM.none "$SYSLOG_CONF" >/dev/null; then
        cp "$SYSLOG_CONF" "$SYSLOG_CONF".new
    else
        awk '
            {print}
            NF >= 2 && ($1 ~ /\.none/ || $2 ~ /\/var\/log\/messages/ || 
                    $2 ~ /\/var\/log\/syslog/) {
                print "'$LOG_LDM'.none	" $2;
            }' "$SYSLOG_CONF" >"$SYSLOG_CONF".new
    fi
    if grep "^$LOG_LDM\." "$SYSLOG_CONF" >/dev/null; then
        : true
    else
        echo >>"$SYSLOG_CONF".new
        echo '# Unidata LDM:' >>"$SYSLOG_CONF".new
        echo "$LOG_LDM.*	$LDM_LOGFILE" >>"$SYSLOG_CONF".new
    fi
    if cmp -s "$SYSLOG_CONF" "$SYSLOG_CONF".new; then
        rm "$SYSLOG_CONF".new
    else
        cp "$SYSLOG_CONF" "$SYSLOG_CONF".old
        mv -f "$SYSLOG_CONF".new "$SYSLOG_CONF"
    fi
}

if fgrep "$LDM_LOGFILE" "$SYSLOG_CONF" >/dev/null; then
    : true
else
    case "$SYSLOG_CONF" in
        *syslog-ng*) modifySyslogNg;;
        *)           modifySyslog;;
    esac
fi