GETLOGIN(2) UNIX Programmer's Manual GETLOGIN(2) NAME getlogin, setlogin - get/set login name SYNOPSIS #include <unistd.h> char * getlogin() int setlogin(name) char *name; DESCRIPTION The getlogin routine returns the login name of the user associated with the current session, as previously set by 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.) Setlogin sets the login name of the user associated with the current session to 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 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 setlogin succeeds, a value of 0 is returned. If 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: EFAULT The name parameter gave an invalid address. EINVAL The name parameter pointed to a string that was too long. Login names are limited to MAXLOGNAME (from <sys/param.h>) characters, currently 16. EPERM The caller tried to set the login name and was not the super-user. SEE ALSO setsid(2) Printed 11/26/99 September 23, 1997 1 GETLOGIN(2) UNIX Programmer's Manual GETLOGIN(2) BUGS Login names are limited in length by setlogin. However, lower limits are placed on login names elsewhere in the sys- tem (UT_NAMESIZE in <utmp.h>). In earlier versions of the system, getlogin failed unless the process was associated with a login terminal. The current implementation (using setlogin) allows getlogin to succeed even when the process has no controlling terminal. In earlier versions of the system, the value returned by getlogin could not be trusted without checking the user ID. Portable programs should probably still make this check. HISTORY The setlogin function first appeared in 4.4BSD. The getlo- gin function was present in V7. Printed 11/26/99 September 23, 1997 2