run_erl(1) User Commands run_erl(1)NAMErun_erl - Redirect Erlang input and output streams on Solaris®
DESCRIPTION
This describes the run_erl program specific to Solaris/Linux. This pro‐
gram 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 sys‐
tem remotely.
You can read more about the use in the Embedded System User's Guide.
EXPORTSrun_erl [-daemon] pipe_dir/ log_dir "exec command [command_arguments]"
The run_erl program arguments are:
-daemon
This option is highly recommended. It makes run_erl run in
the background completely detached from any
controlling
terminal and the command returns to the caller
immediately.
Without this option, run_erl must be started
using several
tricks in the shell to detach it completely
from the
terminal in use when starting it. The option
must be the
first argument to run_erl on the command line.
pipe_dir
This is where to put the named pipe, usually
/tmp/. It shall be suffixed by a / (slash),
i.e. not /tmp/epipies, but /tmp/epipes/.
log_dir
This is where the log files are written. There will be one
log file, 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.
"exec command [command_arguments]"
In the third argument command is the to execute
where everything written to stdin and stdout is
logged to
log_dir.
NOTES CONCERNING THE LOG FILES
While running, run_erl (as stated earlier) sends all output, uninter‐
preted, 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.
ENVIRONMENT VARIABLES
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.
RUN_ERL_LOG_ALIVE_MINUTES
How long to wait for output (in minutes) before writing an
"ALIVE" message to the log. Default is 15, can never be
less
than 1.
RUN_ERL_LOG_ACTIVITY_MINUTES
How long erlang need to be inactive before output will be
preceded with a timestamp. Default is
RUN_ERL_LOG_ALIVE_MINUTES div 3, but never less than 1.
RUN_ERL_LOG_ALIVE_FORMAT
Specifies another format string to be used in the strftime
C library call. i.e specifying this to "%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".
RUN_ERL_LOG_ALIVE_IN_UTC
If set to anything else than "0", it will make all
times displayed by run_erl to be in UTC (GMT,CET,MET,
without
DST), rather than
in local time. This does not affect data coming from
erlang,
only the logs output directly by run_erl. The application
sasl can be modified accordingly by setting the erlang
application variable utc_log to true.
RUN_ERL_LOG_GENERATIONS
Controls the number of log files written before older
files are being reused. Default is 5, minimum is 2, maxi‐
mum is 1000.
RUN_ERL_LOG_MAXSIZE
The size (in bytes) of a log file before switching to a
new log file. Default is 100000, minimum is 1000 and maxi‐
mum is
approximately 2^30.
SEE ALSOstart_embedded(1)Ericsson AB erts 5.7.4 run_erl(1)
