1run_erl(1) User Commands run_erl(1)
2
6 run_erl - Redirect Erlang input and output streams on Unix systems.
7
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
13 remotely.
14 For more information about the use, see the Embedded System User's
16 Guide in System Documentation.
17
19 run_erl [-daemon] pipe_dir/ log_dir "exec command arg1 arg2 ..."
20 Arguments:
22 -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.
31 pipe_dir:
33 The named pipe, usually /tmp/. It must be suffixed by a /
34 (slash), that is, /tmp/epipes/, not /tmp/epipes.
35 log_dir:
37 The log files, that is:
38 * One log file, run_erl.log, which logs progress and warn‐
40 ings from the run_erl program itself.
41 * 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
46 below.)
47 When the logs are full, run_erl deletes and reuses the
49 oldest log file.
50 "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.
55
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
60 erlang.log.(N+1), until N reaches a certain number (default 5), where‐
61 upon N starts at 1 again and the oldest files start getting overwrit‐
62 ten.
63 If no output comes from the Erlang shell, but the Erlang machine still
65 seems to be alive, an "ALIVE" message is written to the log; it is a
66 time stamp and is written, by default, after 15 minutes of inactivity.
67 Also, if output from Erlang is logged, but more than 5 minutes
68 (default) has passed since last time we got anything from Erlang, a
69 time stamp is written in the log. The "ALIVE" messages look as follows:
70 ===== ALIVE <date-time-string>
72 The other time stamps look as follows:
74 ===== <date-time-string>
76 date-time-string is the date and time the message is written, default
78 in local time (can be changed to UTC if needed). It is formatted with
79 the ANSI-C function strftime using the format string %a %b %e %T %Z %Y,
80 which produces messages like ===== ALIVE Thu May 15 10:13:36 MEST 2003;
81 this can be changed, see the next section.
82
84 The following environment variables are recognized by run_erl and
85 change the logging behavior. For more information, see the previous
86 section.
87 RUN_ERL_LOG_ALIVE_MINUTES:
89 How long to wait for output (in minutes) before writing an "ALIVE"
90 message to the log. Defaults to 15, minimum is 1.
91 RUN_ERL_LOG_ACTIVITY_MINUTES:
93 How long Erlang needs to be inactive before output is preceded with
94 a time stamp. Defaults to RUN_ERL_LOG_ALIVE_MINUTES div 3, minimum
95 is 1.
96 RUN_ERL_LOG_ALIVE_FORMAT:
98 Specifies another format string to be used in the strftime C
99 library call. That is, specifying this to "%e-%b-%Y, %T %Z" gives
100 log messages with time stamps like 15-May-2003, 10:23:04 MET. For
101 more information, see the documentation for the C library function
102 strftime. Defaults to "%a %b %e %T %Z %Y".
103 RUN_ERL_LOG_ALIVE_IN_UTC:
105 If set to anything else than 0, it makes all times displayed by
106 run_erl to be in UTC (GMT, CET, MET, without Daylight Saving Time),
107 rather than in local time. This does not affect data coming from
108 Erlang, only the logs output directly by run_erl. Application SASL
109 can be modified accordingly by setting the Erlang application vari‐
110 able utc_log to true.
111 RUN_ERL_LOG_GENERATIONS:
113 Controls the number of log files written before older files are
114 reused. Defaults to 5, minimum is 2, maximum is 1000.
115 Note that, as a way to indicate the newest file, run_erl will
117 delete the oldest log file to maintain a "hole" in the file
118 sequences. For example, if log files #1, #2, #4 and #5 exists, that
119 means #2 is the latest and #4 is the oldest. You will therefore at
120 most get one less log file than the value set by RUN_ERL_LOG_GENER‐
121 ATIONS.
122 RUN_ERL_LOG_MAXSIZE:
124 The size, in bytes, of a log file before switching to a new log
125 file. Defaults to 100000, minimum is 1000, maximum is about 2^30.
126 RUN_ERL_DISABLE_FLOWCNTRL:
128 If defined, disables input and output flow control for the pty
129 opend by run_erl. Useful if you want to remove any risk of acciden‐
130 tally blocking the flow control by using Ctrl-S (instead of Ctrl-D
131 to detach), which can result in blocking of the entire Beam
132 process, and in the case of running heart as supervisor even the
133 heart process becomes blocked when writing log message to terminal,
134 leaving the heart process unable to do its work.
135
137 start(1), start_erl(1)
138Ericsson AB erts 11.2 run_erl(1)