Linux / Unix Command: cuserid

Command Library

NAME

getlogin, cuserid - get user name  

SYNOPSIS

#include <unistd.h>

char *getlogin(void);

#include <stdio.h>

char *cuserid(char *string);  

DESCRIPTION

getlogin returns a pointer to a string containing the name of the user logged in on the controlling terminal of the process, or a null pointer if this information cannot be determined. The string is statically allocated and might be overwritten on subsequent calls to this function or to cuserid.

cuserid returns a pointer to a string containing a user name associated with the effective user ID of the process. If string is not a null pointer, it should be an array that can hold at least L_cuserid characters; the string is returned in this array. Otherwise, a pointer to a string in a static area is returned. This string is statically allocated and might be overwritten on subsequent calls to this function or to getlogin.

The macro L_cuserid is an integer constant that indicates how long an array you might need to store a user name. L_cuserid is declared in stdio.h.

These functions let your program identify positively the user who is running (cuserid) or the user who logged in this session (getlogin). (These can differ when setuid programs are involved.)

For most purposes, it is more useful to use the environment variable LOGNAME to find out who the user is. This is more flexible precisely because the user can set LOGNAME arbitrarily.  

ERRORS

ENOMEM

Insufficient memory to allocate passwd structure.

 

SEE ALSO

geteuid(2), getuid(2)

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