I'd like to be able to get an email notification whenever syslogd logs something of, say err priority or higher. Assume this is a BSD compatible syslog daemon.

  • Can this be accomplished?
  • Should I use a named pipe to a shell script?
  • What other possible solutions are there?

Here's a solution that uses named pipes. It is set up for Debian, but you should be able to modify it for BSD.

  • Ended up basing my solution on this so I could daemonize the emailing. Thanks for the link.
    – jason
    Jun 26 '09 at 22:46
  • This seems too much of a hack. Why would you spend time scripting when there is stable open source apps to do that for you? (in real time too). *see my reply.
    – sucuri
    Jun 29 '09 at 2:07
  • 2
    Not a hack at all. It's the way this kind of thing often gets done. Jun 29 '09 at 3:04
  • Link doesn't seem to work.
    – Yd Ahhrk
    Apr 15 at 20:25

Notifications via syslogd(8)

On my OpenBSD server, I log and email important messages from my web applications, which use facility local1. Here is my /etc/syslog.conf to make it happen:

local1.err    /var/log/example.com
local1.err    |while read log; do echo "$log" | /usr/bin/mail -s SYSLOG me@example.com; done

Notice that the while loop infinitely reads each line from syslogd and then pipes it to mail via echo. This is important. Once echo outputs its line it terminates the pipe, sending mail an EOF so it can email the log message.

In other words, you can't pipe directly to mail via syslogd like so:

local1.err    |/usr/bin/mail -s SYSLOG me@example.com

because syslogd will continue writing to the pipe until it is itself terminated or sent a HUP signal, at which time mail would send the entire set of log messages in one big email.

Notifications via newsyslog(8)

Scheduling newsyslog in cron is another way to get messages at a slower rate or in bulk.

For example, if you wanted a daily email digest of the log messages, set the M flag and specifying a monitor email address in /etc/newsyslog.conf:

# logfile_name        owner:group  mode  count  size  when  flags  monitor
/var/log/example.com  root:wheel   640   7      *     24    M      me@example.com

Then schedule newsyslog in crontab:

# minute hour  mday  month  wday  command
0        *     *     *      *     /usr/bin/newsyslog
1-59     *     *     *      *     /usr/bin/newsyslog -m

The -m option for newsyslog(8) states:

Monitoring mode; only entries marked with an `M' in flags are processed. For each log file being monitored, any log output since the last time newsyslog was run with the -m flag is mailed to the user listed in the monitor notification section.


You may want to look at logcheck or logwatch. Logcheck will email you hourly with log lines that don't match a set of patterns. I suspect you could probably make it do it more frequently. I don't know of any tools that do it by watching the logfiles, but I'm sure there's something out there that does it.

  • Yeah, I'd prefer not to monitor and parse log files after they are written, but just hook into the logging process so I can get instant notifications.
    – jason
    Jun 26 '09 at 19:29

I would use OSSEC. It monitors your logs in real time and allows you to easily alert by email (or other means) when specific events are matched. Simple to use, scalable and open source.

link: http://www.ossec.net

  • This may be overkill for the application. However, the package does a lot and if there's a need then it may be a fit. Jun 29 '09 at 3:03

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