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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | ATTRIBUTES | STANDARDS | HISTORY | BUGS | SEE ALSO | COLOPHON |
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rexec(3) Library Functions Manual rexec(3)
rexec, rexec_af - return stream to a remote command
Standard C library (libc, -lc)
#include <netdb.h>
[[deprecated]]
int rexec(char **restrict ahost, int inport,
const char *restrict user, const char *restrict passwd,
const char *restrict cmd, int *restrict fd2p);
[[deprecated]]
int rexec_af(char **restrict ahost, int inport,
const char *restrict user, const char *restrict passwd,
const char *restrict cmd, int *restrict fd2p,
sa_family_t af);
rexec(), rexec_af():
Since glibc 2.19:
_DEFAULT_SOURCE
In glibc up to and including 2.19:
_BSD_SOURCE
This interface is obsoleted by rcmd(3).
The rexec() function looks up the host *ahost using
gethostbyname(3), returning -1 if the host does not exist.
Otherwise, *ahost is set to the standard name of the host. If a
username and password are both specified, then these are used to
authenticate to the foreign host; otherwise the environment and
then the .netrc file in user's home directory are searched for
appropriate information. If all this fails, the user is prompted
for the information.
The port inport specifies which well-known DARPA Internet port to
use for the connection; the call getservbyname("exec", "tcp") (see
getservent(3)) will return a pointer to a structure that contains
the necessary port. The protocol for connection is described in
detail in rexecd(8).
If the connection succeeds, a socket in the Internet domain of
type SOCK_STREAM is returned to the caller, and given to the
remote command as stdin and stdout. If fd2p is nonzero, then an
auxiliary channel to a control process will be setup, and a file
descriptor for it will be placed in *fd2p. The control process
will return diagnostic output from the command (unit 2) on this
channel, and will also accept bytes on this channel as being UNIX
signal numbers, to be forwarded to the process group of the
command. The diagnostic information returned does not include
remote authorization failure, as the secondary connection is set
up after authorization has been verified. If fd2p is 0, then the
stderr (unit 2 of the remote command) will be made the same as the
stdout and no provision is made for sending arbitrary signals to
the remote process, although you may be able to get its attention
by using out-of-band data.
rexec_af()
The rexec() function works over IPv4 (AF_INET). By contrast, the
rexec_af() function provides an extra argument, af, that allows
the caller to select the protocol. This argument can be specified
as AF_INET, AF_INET6, or AF_UNSPEC (to allow the implementation to
select the protocol).
For an explanation of the terms used in this section, see
attributes(7).
┌────────────────────────────────────┬───────────────┬───────────┐
│ Interface │ Attribute │ Value │
├────────────────────────────────────┼───────────────┼───────────┤
│ rexec(), rexec_af() │ Thread safety │ MT-Unsafe │
└────────────────────────────────────┴───────────────┴───────────┘
None.
rexec()
4.2BSD, BSD, Solaris.
rexec_af()
glibc 2.2.
The rexec() function sends the unencrypted password across the
network.
The underlying service is considered a big security hole and
therefore not enabled on many sites; see rexecd(8) for
explanations.
rcmd(3), rexecd(8)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.15 2025-05-17 rexec(3)
Pages that refer to this page: rcmd(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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