1REXEC(3)                   Linux Programmer's Manual                  REXEC(3)
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3
4

NAME

6       rexec, rexec_af - return stream to a remote command
7

SYNOPSIS

9       #include <netdb.h>
10
11       int rexec(char **ahost, int inport, const char *user,
12                 const char *passwd, const char *cmd, int *fd2p);
13
14       int rexec_af(char **ahost, int inport, const char *user,
15                    const char *passwd, const char *cmd, int *fd2p,
16                    sa_family_t af);
17
18       rexec(), rexec_af():
19           Since glibc 2.19:
20               _DEFAULT_SOURCE
21           In glibc up to and including 2.19:
22               _BSD_SOURCE
23

DESCRIPTION

25       This interface is obsoleted by rcmd(3).
26
27       The  rexec()  function looks up the host *ahost using gethostbyname(3),
28       returning -1 if the host does not exist.  Otherwise, *ahost is  set  to
29       the  standard  name  of  the host.  If a username and password are both
30       specified, then these are used to authenticate  to  the  foreign  host;
31       otherwise  the  environment  and  then  the  .netrc file in user's home
32       directory are searched for appropriate information.  If all this fails,
33       the user is prompted for the information.
34
35       The  port  inport specifies which well-known DARPA Internet port to use
36       for the connection; the call getservbyname("exec", "tcp") (see  getser‐
37       vent(3))  will return a pointer to a structure that contains the neces‐
38       sary port.  The protocol for connection is described in detail in  rex‐
39       ecd(8).
40
41       If  the  connection  succeeds,  a socket in the Internet domain of type
42       SOCK_STREAM is returned to the caller, and given to the remote  command
43       as  stdin and stdout.  If fd2p is nonzero, then an auxiliary channel to
44       a control process will be setup, and a file descriptor for it  will  be
45       placed  in  *fd2p.   The  control process will return diagnostic output
46       from the command (unit 2) on this channel, and will also  accept  bytes
47       on  this  channel  as being UNIX signal numbers, to be forwarded to the
48       process group of the command.  The diagnostic information returned does
49       not  include  remote authorization failure, as the secondary connection
50       is set up after authorization has been verified.  If fd2p  is  0,  then
51       the  stderr (unit 2 of the remote command) will be made the same as the
52       stdout and no provision is made for sending arbitrary  signals  to  the
53       remote  process, although you may be able to get its attention by using
54       out-of-band data.
55
56   rexec_af()
57       The rexec() function works  over  IPv4  (AF_INET).   By  contrast,  the
58       rexec_af()  function  provides  an  extra argument, af, that allows the
59       caller to select the protocol.   This  argument  can  be  specified  as
60       AF_INET,  AF_INET6, or AF_UNSPEC (to allow the implementation to select
61       the protocol).
62

VERSIONS

64       The rexec_af() function was added to glibc in version 2.2.
65

ATTRIBUTES

67       For  an  explanation  of  the  terms  used   in   this   section,   see
68       attributes(7).
69
70       ┌────────────────────┬───────────────┬───────────┐
71Interface           Attribute     Value     
72       ├────────────────────┼───────────────┼───────────┤
73rexec(), rexec_af() │ Thread safety │ MT-Unsafe │
74       └────────────────────┴───────────────┴───────────┘

CONFORMING TO

76       These  functions  are  not  in  POSIX.1.   The  rexec()  function first
77       appeared in 4.2BSD, and is present on the BSDs, Solaris, and many other
78       systems.  The rexec_af() function is more recent, and less widespread.
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BUGS

81       The rexec() function sends the unencrypted password across the network.
82
83       The  underlying service is considered a big security hole and therefore
84       not enabled on many sites; see rexecd(8) for explanations.
85

SEE ALSO

87       rcmd(3), rexecd(8)
88

COLOPHON

90       This page is part of release 5.02 of the Linux  man-pages  project.   A
91       description  of  the project, information about reporting bugs, and the
92       latest    version    of    this    page,    can     be     found     at
93       https://www.kernel.org/doc/man-pages/.
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97Linux                             2017-09-15                          REXEC(3)
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