1REXEC(3) Linux Programmer's Manual REXEC(3)
2
6 rexec, rexec_af - return stream to a remote command
7
9 #define _BSD_SOURCE /* See feature_test_macros(7) */
10 #include <netdb.h>
11 int rexec(char **ahost, int inport, char *user,
13 char *passwd, char *cmd, int *fd2p);
14 int rexec_af(char **ahost, int inport, char *user,
16 char *passwd, char *cmd, int *fd2p,
17 sa_family_t af);
18
20 This interface is obsoleted by rcmd(3).
21 The rexec() function looks up the host *ahost using gethostbyname(3),
23 returning -1 if the host does not exist. Otherwise *ahost is set to
24 the standard name of the host. If a username and password are both
25 specified, then these are used to authenticate to the foreign host;
26 otherwise the environment and then the user's .netrc file in his home
27 directory are searched for appropriate information. If all this fails,
28 the user is prompted for the information.
29 The port inport specifies which well-known DARPA Internet port to use
31 for the connection; the call getservbyname("exec", "tcp") (see getser‐
32 vent(3)) will return a pointer to a structure that contains the neces‐
33 sary port. The protocol for connection is described in detail in rex‐
34 ecd(8).
35 If the connection succeeds, a socket in the Internet domain of type
37 SOCK_STREAM is returned to the caller, and given to the remote command
38 as stdin and stdout. If fd2p is nonzero, then an auxiliary channel to
39 a control process will be setup, and a descriptor for it will be placed
40 in *fd2p. The control process will return diagnostic output from the
41 command (unit 2) on this channel, and will also accept bytes on this
42 channel as being UNIX signal numbers, to be forwarded to the process
43 group of the command. The diagnostic information returned does not
44 include remote authorization failure, as the secondary connection is
45 set up after authorization has been verified. If fd2p is 0, then the
46 stderr (unit 2 of the remote command) will be made the same as the std‐
47 out and no provision is made for sending arbitrary signals to the
48 remote process, although you may be able to get its attention by using
49 out-of-band data.
50 rexec_af()
52 The rexec() function works over IPv4 (AF_INET). By contrast, the
53 rexec_af() function provides an extra argument, af, that allows the
54 caller to select the protocol. This argument can be specified as
55 AF_INET, AF_INET6, or AF_UNSPEC (to allow the implementation to select
56 the protocol).
57
59 The rexec_af() function was added to glibc in version 2.2.
60
62 Multithreading (see pthreads(7))
63 The rexec() and rexec_af() functions are not thread-safe.
64
66 These functions are not in POSIX.1-2001. The rexec() function first
67 appeared in 4.2BSD, and is present on the BSDs, Solaris, and many other
68 systems. The rexec_af() function is more recent, and less widespread.
69
71 The rexec() function sends the unencrypted password across the network.
72 The underlying service is considered a big security hole and therefore
74 not enabled on many sites; see rexecd(8) for explanations.
75
77 rcmd(3), rexecd(8)
78
80 This page is part of release 3.53 of the Linux man-pages project. A
81 description of the project, and information about reporting bugs, can
82 be found at http://www.kernel.org/doc/man-pages/.
83Linux 2013-07-04 REXEC(3)