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setuid(2)
NAME
  setuid - Set the user ID

SYNOPSIS
  #include <unistd.h>

  int setuid(
	  uid_t user_id );

  Application developers may want to specify an #include statement for
  <sys/types.h> before the one for <unistd.h> if programs are being developed
  for multiple platforms. The additional #include statement is not required
  on Tru64 UNIX systems or by ISO or XSH standards, but may be required on
  other vendors' systems that conform to these standards.

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  setuid(): XSH4.0, XSH4.2, XSH5.0

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  user_id
      Specifies the new user ID.

DESCRIPTION
  The setuid() function sets the real user ID, effective user ID, and the
  saved set user ID to the user_id parameter.

  To change the real user ID, the effective user ID, and the saved set user
  ID, the calling process must have superuser privilege. If the process does
  not have appropriate privilege, but the user_id parameter is equal to the
  real user ID or the saved set user ID, the setuid() function sets the
  effective user ID to the user_id parameter. The real user ID and saved set
  user ID remain unchanged.

RETURN VALUES
  Upon successful completion, the setuid() function returns a value of 0
  (zero). Otherwise, the function returns a value of -1 and sets errno to
  indicate the error.

ERRORS
  The setuid() function sets errno to the specified values for the following
  conditions:

  [EAGAIN]
      [Tru64 UNIX]  The process is attempting an operation that would exceeds
      a system limit, such as the number of tasks or threads allowed for a
      user ID.

  [EINVAL]
      The value of the user_id parameter is invalid.

  [EPERM]
      The process does not have superuser privileges, and the user_id
      parameter does not match the real user ID or the saved set user ID.

SEE ALSO
  Functions: exec(2), getuid(2), setgid(2), setreuid(2)

  Standards: standards(5)

Index for Section 2

Alphabetical listing for S

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