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rexec(3) — Linux manual page

rexec(3)                 Library Functions Manualrexec(3)

NAME        top

       rexec, rexec_af - return stream to a remote command

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <netdb.h>[[deprecated]]int rexec(char **restrictahost, intinport,const char *restrictuser, const char *restrictpasswd,const char *restrictcmd, int *restrictfd2p);[[deprecated]]int rexec_af(char **restrictahost, intinport,const char *restrictuser, const char *restrictpasswd,const char *restrictcmd, int *restrictfd2p,sa_family_taf);rexec(),rexec_af():           Since glibc 2.19:               _DEFAULT_SOURCE           In glibc up to and including 2.19:               _BSD_SOURCE

DESCRIPTION        top

       This interface is obsoleted byrcmd(3).       Therexec() function looks up the host*ahost usinggethostbyname(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 portinport specifies which well-known DARPA Internet port to       use for the connection; the callgetservbyname("exec", "tcp") (seegetservent(3)) will return a pointer to a structure that contains       the necessary port.  The protocol for connection is described in       detail inrexecd(8).       If the connection succeeds, a socket in the Internet domain of       typeSOCK_STREAMis returned to the caller, and given to the       remote command asstdin andstdout.  Iffd2p 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.  Iffd2p is 0, then thestderr (unit 2 of the remote command) will be made the same as thestdout 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()       Therexec() function works over IPv4 (AF_INET).  By contrast, therexec_af() function provides an extra argument,af, that allows       the caller to select the protocol.  This argument can be specified       asAF_INET,AF_INET6, orAF_UNSPEC(to allow the implementation to       select the protocol).

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌────────────────────────────────────┬───────────────┬───────────┐       │Interface│Attribute│Value│       ├────────────────────────────────────┼───────────────┼───────────┤       │rexec(),rexec_af()                │ Thread safety │ MT-Unsafe │       └────────────────────────────────────┴───────────────┴───────────┘

STANDARDS        top

       None.

HISTORY        top

rexec()              4.2BSD, BSD, Solaris.rexec_af()              glibc 2.2.

BUGS        top

       Therexec() function sends the unencrypted password across the       network.       The underlying service is considered a big security hole and       therefore not enabled on many sites; seerexecd(8) for       explanations.

SEE ALSO        top

rcmd(3),rexecd(8)

COLOPHON        top

       This page is part of theman-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 isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17rexec(3)

Pages that refer to this page:rcmd(3)

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