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getlogin(2)
NAME
  getlogin, getlogin_r, setlogin - Gets and sets login name

SYNOPSIS
  #include <unistd.h>

  char *getlogin(void);

  int getlogin_r(
	  char *name,
	  size_t len);

  int setlogin(
	  char *name);

  The following function does not conform to current standards and is
  supported only for backward compatibility:

  int getlogin_r(char *name, int len);

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

  getlogin(), getlogin_r(): XSH5.0

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

PARAMETERS
  name	    Points to the login name.

  len	    Specifies the length of the buffer pointed to by name.

DESCRIPTION
  The getlogin() function returns the login name of the user associated with
  the current session.	The name is normally associated with a login shell at
  the time a session is created, and is inherited by all processes descended
  from the login shell.	 (This is true even if some of those processes assume
  another user ID, for example when the su command is used.)

  The setlogin() function sets the login name of the user associated with the
  current session to name.  This call is restricted to the superuser, and is
  normally used only when a new session is being created on behalf of the
  named user (for example, at login time, or when a remote shell is invoked).

  The getlogin_r() function is the reentrant version of getlogin().  Upon
  successful completion, the login name is stored in name.

RETURN VALUES
  Upon successful completion, the getlogin() function returns a pointer to a
  null-terminated string in a static buffer or a null pointer if the user's
  login name cannot be found.  If getlogin() fails, a null pointer is
  returned, and errno is set to indicate the error.

  Upon successful completion, the setlogin() function returns a value of 0
  (zero).  If setlogin() fails, then a value of -1 is returned and an error
  code is placed in errno.

  Upon successful completion, the getlogin_r() function returns a value of 0
  (zero).  Otherwise, an error number is returned.

  [Tru64 UNIX]	Upon successful completion, the obsolete version of the
  getlogin_r() function returns a value of 0 (zero).  Otherwise, -1 is
  returned and errno is set to indicate the error.

ERRORS
  If the getlogin(), getlogin_r(), or setlogin() function fails, errno may be
  set to one of the following values:

  [EFAULT]  [Tru64 UNIX]  The name parameter gave an invalid address.

  [EINVAL]  [Tru64 UNIX]  The name parameter pointed to a string that was too
	    long.

	    [Tru64 UNIX]  Login names are limited to 64 characters, as
	    specified by MAXLOGNAME (which is defined in sys/user.h).
	    However, this name limit must be enabled in the kernel at boot
	    time by explicitly setting the generic subsystem's login_name_max
	    attribute to 64. For backward compatibility reasons, 12 is the
	    default value of the login_name_max attribute.

  An additional value for a setlogin() failure is the following:

  [EPERM]   [Tru64 UNIX]   The caller tried to set the login name and was not
	    the superuser.

RELATED INFORMATION
  Commands: su(1)

  Functions: setsid(2)

  Standards: standards(5)

Index for Section 2

Alphabetical listing for G

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