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This describes the run_erl program specific to
Solaris/Linux. This program redirect the standard input and standard
output streams so that all output can be logged. It also let the
program to_erl connect to the Erlang console making it
possible to monitor and debug an embedded system remotely.
You can read more about the use in the Embedded System User's
Guide.
run_erl [-daemon] pipe_dir/ log_dir "exec command [command_arguments]"
The run_erl program arguments are:
/tmp/. It shall be suffixed by a / (slash),
i.e. not /tmp/epipies, but /tmp/epipes/.
run_erl.log that log progress and
warnings from the run_erl program itself and there
will be up to five log files at maximum 100KB each (both
number of logs and sizes can be
changed by environment variables, see below) with
the content of the standard streams from and to the
command. When the logs are full run_erl will delete
and reuse the oldest log file.
command is the to execute
where everything written to stdin and stdout is logged to
log_dir.
While running, run_erl (as stated earlier) sends all output,
uninterpreted, to a log file. The file is called
erlang.log.N, where N is a number. When the log is "full",
default after 100KB, run_erl starts to log in file
erlang.log.(N+1), until N reaches a certain number (default
5), where after N starts at 1 again and the oldest files start
getting overwritten. If no output comes from the erlang shell, but
the erlang machine still seems to be alive, an "ALIVE" message is
written to the log, it is a timestamp and is written, by default,
after 15 minutes of inactivity. Also, if output from erlang is
logged but it's been more than 5 minutes (default) since last time
we got anything from erlang, a timestamp is written in the
log. The "ALIVE" messages look like this:
===== ALIVE <date-time-string>
while the other timestamps look like this:
===== <date-time-string>
The date-time-string is the date and time the message is
written, default in local time (can be changed to GMT if one wants
to) and is formatted with the ANSI-C function strftime
using the format string %a %b %e %T %Z %Y, which produces
messages on the line of ===== ALIVE Thu May 15 10:13:36 MEST
2003, this can be changed, see below.
The following environment variables are recognized by run_erl and change the logging behavior. Also see the notes above to get more info on how the log behaves.
"%e-%b-%Y, %T %Z"
will give log messages with timestamps looking like
15-May-2003, 10:23:04 MET etc. See the documentation
for the C library function strftime for more
information. Default is "%a %b %e %T %Z %Y".
sasl can be modified accordingly by setting the erlang
application variable utc_log to true.
start(1), start_erl(1)