getlogin, getlogin_r, setlogin - Gets and sets login name
The following function does not conform to current standards and is sup-
ported only for backward compatibility:
int getlogin_r(char *name, int len);
Interfaces documented on this reference page conform to industry standards
getlogin(), getlogin_r(): XSH5.0
Refer to the standards(5) reference page for more information about indus-
try standards and associated tags.
name Points to the login name.
len Specifies the length of the buffer pointed to by name.
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.
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.
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
[Tru64 UNIX] Login names are limited to 64 characters, as speci-
fied 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 attri-
bute 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