GETLOGIN

Section: System Calls (2)
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BSD mandoc
BSD 4.2

NAME

getlogin setlogin - get/set login name

SYNOPSIS

Fd #include <unistd.h> Ft char * Fn getlogin void Ft int Fn setlogin const char *name

DESCRIPTION

The Fn getlogin routine returns the login name of the user associated with the current session, as previously set by Fn setlogin . 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 su(1) is used.)

Fn Setlogin sets the login name of the user associated with the current session to Fa name . This call is restricted to the super-user, 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).

RETURN VALUES

If a call to Fn getlogin succeeds, it returns a pointer to a null-terminated string in a static buffer. If the name has not been set, it returns NULL If a call to Fn setlogin succeeds, a value of 0 is returned. If Fn setlogin fails, a value of -1 is returned and an error code is placed in the global location errno

ERRORS

The following errors may be returned by these calls:

Bq Er EFAULT: The Fa name parameter gave an invalid address.
Bq Er EINVAL: The Fa name parameter pointed to a string that was too long. Login names are limited to MAXLOGNAME (from Ao Pa sys/param.h Ac ) characters, currently 12.
Bq Er EPERM: The caller tried to set the login name and was not the super-user.

BUGS

Login names are limited in length by Fn setlogin . However, lower limits are placed on login names elsewhere in the system ( UT_NAMESIZE in Ao Pa utmp.h Ac ) .

In earlier versions of the system, Fn getlogin failed unless the process was associated with a login terminal. The current implementation (using Fn setlogin ) allows getlogin to succeed even when the process has no controlling terminal. In earlier versions of the system, the value returned by Fn getlogin could not be trusted without checking the user ID. Portable programs should probably still make this check.

HISTORY

The Fn getlogin function first appeared in 4.4BSD.

This document was created by man2html, using the manual pages.
Time: 16:28:59 GMT, April 18, 2022