1REMCTL_OUTPUT(3) remctl Library Reference REMCTL_OUTPUT(3)
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6 remctl_output - Retrieve the results of a remctl command
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9 #include <remctl.h>
10 struct remctl_output *remctl_output(struct remctl *r);
12
14 remctl_output() retrieves the next output token from the remote remctl
15 server. r is a remctl client object created with remctl_new(), which
16 should have previously been used as the argument to remctl_open() and
17 then either remctl_command() or remctl_commandv().
18 The returned remctl_output struct has the following members:
20 struct remctl_output {
22 enum remctl_output_type type;
23 char *data;
24 size_t length;
25 int stream; /* 1 == stdout, 2 == stderr */
26 int status; /* Exit status of remote command. */
27 int error; /* Remote error code. */
28 };
29 where the type field will have one of the following values:
31 REMCTL_OUT_OUTPUT
33 REMCTL_OUT_STATUS
34 REMCTL_OUT_ERROR
35 REMCTL_OUT_DONE
36 A command rejected by the remctl server will return a single output
38 token of type REMCTL_OUT_ERROR. A successful command will return zero
39 or more REMCTL_OUT_OUTPUT tokens representing the output of the command
40 followed by a REMCTL_OUT_STATUS token giving the exit status of the
41 command. Therefore, for each command issued, the caller should call
42 remctl_command() or remctl_commandv() and then call remctl_output()
43 repeatedly to retrieve each output token until remctl_output() returns
44 a token of type REMCTL_OUT_ERROR or REMCTL_OUT_STATUS.
45 A REMCTL_OUT_OUTPUT token will have data in the data field, whose
47 length is given by the length field. The output stream will be given
48 by the stream field, with a value of 1 indicating standard output and a
49 value of 2 indicating standard error. All other stream values are
50 reserved for future use.
51 A REMCTL_OUT_STATUS token will hold the exit status of the remote com‐
53 mand in the status field. Following the standard Unix convention, a 0
54 status should normally be considered success and any non-zero status
55 should normally be considered failure, although a given command may
56 have its own exit status conventions.
57 A REMCTL_OUT_ERROR token will have the error message from the server in
59 the data field (with length stored in length) and the protocol error
60 code in the error field. The latter is the most reliable indicator of
61 the error; the message stored in the error field is free-form text, may
62 or may not be localized, and should not be used for programmatic com‐
63 parisons. For the possible error code values and their meanings, see
64 the remctl protocol specification.
65 If remctl_output() is called when there is no pending output from the
67 remote server (after a REMCTL_OUT_ERROR or REMCTL_OUT_STATUS token has
68 already been returned, for example), a token of type REMCTL_OUT_DONE
69 will be returned. REMCTL_OUT_DONE tokens do not use any of the other
70 fields of the remctl_output struct.
71 The returned remctl_output struct must not be freed by the caller. It
73 will be invalidated on any subsequent call to any other remctl API
74 function other than remctl_error() on the same remctl client object;
75 the caller should therefore copy out of the remctl_output struct any
76 data it wishes to preserve before making any subsequent remctl API
77 calls.
78
80 remctl_output() returns a pointer to a remctl_output struct on success
81 and NULL on failure. On failure, the caller should call remctl_error()
82 to retrieve the error message.
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85 remctl_new(3), remctl_open(3), remctl_command(3), remctl_commandv(3),
86 remctl_error(3)
87 The current version of the remctl library and complete details of the
89 remctl protocol are available from its web page at
90 <http://www.eyrie.org/~eagle/software/remctl/>.
91
93 Russ Allbery <rra@stanford.edu>
942.11 2007-06-29 REMCTL_OUTPUT(3)