getlogin, getlogin_r, setlogin - Gets and sets login name
The following function does not conform to current standards and is supported only for backward compatibility:
int getlogin_r(char*name, int len);
Interfaces documented on this reference page conform to industry standards as follows:
getlogin(): XPG4, XPG4-UNIX
Refer to the standards(5) reference page for more information about industry standards and associated tags.
Points to the login name. 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.)
[Digital] 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).
[POSIX] 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.
[POSIX] Upon successful completion, the getlogin_r() function returns a value of 0 (zero). Otherwise, an error number is returned.
[Digital] 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: [Digital] The name parameter gave an invalid address. [Digital] The name parameter pointed to a string that was too long. Login names are limited to MAXLOGNAME characters (defined in sys/user.h). [Digital] The caller tried to set the login name and was not the superuser.
Standards: standards(5) delim off