1run_erl(1)                       User Commands                      run_erl(1)
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NAME

6       run_erl - Redirect Erlang input and output streams on Unix systems.
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DESCRIPTION

9       The run_erl program is specific to Unix systems. This program redirects
10       the standard input and standard output streams so that all  output  can
11       be  logged.  It also lets the program to_erl connect to the Erlang con‐
12       sole, making it possible to monitor and debug an  embedded  system  re‐
13       motely.
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15       For  more  information  about  the use, see the  Embedded System User's
16       Guide in System Documentation.
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EXPORTS

19       run_erl [-daemon] pipe_dir/ log_dir "exec command arg1 arg2 ..."
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21              Arguments:
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23                -daemon:
24                  This option is highly recommended. It makes run_erl  run  in
25                  the background completely detached from any controlling ter‐
26                  minal and the command returns  to  the  caller  immediately.
27                  Without  this  option, run_erl must be started using several
28                  tricks in the shell to detach it completely from the  termi‐
29                  nal  in  use  when starting it. The option must be the first
30                  argument to run_erl on the command line.
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32                pipe_dir:
33                  The named pipe, usually /tmp/. It must be suffixed  by  a  /
34                  (slash), that is, /tmp/epipes/, not /tmp/epipes.
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36                log_dir:
37                  The log files, that is:
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39                  * One  log  file, run_erl.log, which logs progress and warn‐
40                    ings from the run_erl program itself.
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42                  * Up to five log files at maximum 100 KB each with the  con‐
43                    tent  of  the  standard  streams  from and to the command.
44                    (Both the number of logs and sizes can be changed by envi‐
45                    ronment  variables,  see section Environment Variables be‐
46                    low.)
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48                    When the logs are full, run_erl  deletes  and  reuses  the
49                    oldest log file.
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51                "exec command arg1 arg2 ...":
52                  A  space-separated  string specifying the program to be exe‐
53                  cuted. The second field is typically a command name such  as
54                  erl.
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NOTES CONCERNING THE LOG FILES

57       While  running, run_erl sends all output, uninterpreted, to a log file.
58       The file is named erlang.log.N, where N is an integer. When the log  is
59       "full"  (default log size is 100 KB), run_erl starts to log in file er‐
60       lang.log.(N+1), until N reaches a certain number (default 5), whereupon
61       N starts at 1 again and the oldest files start getting overwritten.
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63       If  no output comes from the Erlang shell, but the Erlang machine still
64       seems to be alive, an "ALIVE" message is written to the log;  it  is  a
65       time  stamp and is written, by default, after 15 minutes of inactivity.
66       Also, if output from Erlang is logged, but more  than  5  minutes  (de‐
67       fault)  has  passed since last time we got anything from Erlang, a time
68       stamp is written in the log. The "ALIVE" messages look as follows:
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70       ===== ALIVE <date-time-string>
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72       The other time stamps look as follows:
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74       ===== <date-time-string>
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76       date-time-string is the date and time the message is  written,  default
77       in  local  time (can be changed to UTC if needed). It is formatted with
78       the ANSI-C function strftime using the format string %a %b %e %T %Z %Y,
79       which produces messages like ===== ALIVE Thu May 15 10:13:36 MEST 2003;
80       this can be changed, see the next section.
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ENVIRONMENT VARIABLES

83       The following environment  variables  are  recognized  by  run_erl  and
84       change  the  logging  behavior.  For more information, see the previous
85       section.
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87         RUN_ERL_LOG_ALIVE_MINUTES:
88           How long to wait for output (in minutes) before writing an  "ALIVE"
89           message to the log. Defaults to 15, minimum is 1.
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91         RUN_ERL_LOG_ACTIVITY_MINUTES:
92           How long Erlang needs to be inactive before output is preceded with
93           a time stamp. Defaults to RUN_ERL_LOG_ALIVE_MINUTES div 3,  minimum
94           is 1.
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96         RUN_ERL_LOG_ALIVE_FORMAT:
97           Specifies  another  format  string to be used in the strftime C li‐
98           brary call. That is, specifying this to "%e-%b-%Y, %T %Z" gives log
99           messages  with time stamps like 15-May-2003, 10:23:04 MET. For more
100           information, see the documentation for the C library function strf‐
101           time. Defaults to "%a %b %e %T %Z %Y".
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103         RUN_ERL_LOG_ALIVE_IN_UTC:
104           If  set  to  anything  else than 0, it makes all times displayed by
105           run_erl to be in UTC (GMT, CET, MET, without Daylight Saving Time),
106           rather  than  in  local time. This does not affect data coming from
107           Erlang, only the logs output directly by run_erl. Application  SASL
108           can be modified accordingly by setting the Erlang application vari‐
109           able utc_log to true.
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111         RUN_ERL_LOG_GENERATIONS:
112           Controls the number of log files written  before  older  files  are
113           reused. Defaults to 5, minimum is 2, maximum is 1000.
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115           Note  that,  as  a  way  to  indicate the newest file, run_erl will
116           delete the oldest log file to maintain a "hole"  in  the  file  se‐
117           quences.  For  example, if log files #1, #2, #4 and #5 exists, that
118           means #2 is the latest and #4 is the oldest. You will therefore  at
119           most get one less log file than the value set by RUN_ERL_LOG_GENER‐
120           ATIONS.
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122         RUN_ERL_LOG_MAXSIZE:
123           The size, in bytes, of a log file before switching  to  a  new  log
124           file. Defaults to 100000, minimum is 1000, maximum is about 2^30.
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126         RUN_ERL_DISABLE_FLOWCNTRL:
127           If  defined,  disables  input  and  output flow control for the pty
128           opend by run_erl. Useful if you want to remove any risk of acciden‐
129           tally  blocking the flow control by using Ctrl-S (instead of Ctrl-D
130           to detach), which  can  result  in  blocking  of  the  entire  Beam
131           process,  and  in  the case of running heart as supervisor even the
132           heart process becomes blocked when writing log message to terminal,
133           leaving the heart process unable to do its work.
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SEE ALSO

136       start(1), start_erl(1)
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140Ericsson AB                       erts 14.1.1                       run_erl(1)
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