SYNOPSIS<\/a>
DESCRIPTION<\/a>
RETURN VALUE<\/a>
ERRORS<\/a>
FILES<\/a>
ATTRIBUTES<\/a>
CONFORMING TO<\/a>
BUGS<\/a>
SEE ALSO<\/a>
COLOPHON<\/a> <\/p>\n
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NAME <\/a> <\/h2>\ngetlogin, getlogin_r, cuserid \u2212 get username<\/p>\n
SYNOPSIS <\/a> <\/h2>\n#include <\/b><\/p>\nchar *getlogin(void);
int getlogin_r(char *<\/b>buf<\/i>, size_t<\/b> bufsize<\/i>);<\/b><\/p>\n
#include <\/b><\/p>\nchar *cuserid(char *<\/b>string<\/i>);<\/b><\/p>\n
Feature Test Macro Requirements for glibc (see feature_test_macros<\/b>(7)):<\/p>\n
getlogin_r<\/b>(): _POSIX_C_SOURCE\u00a0>=\u00a0199506L<\/p>\n
cuserid<\/b>():
Since glibc 2.24:
(_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
|| _GNU_SOURCE
Up to and including glibc 2.23:
_XOPEN_SOURCE<\/p>\nDESCRIPTION <\/a> <\/h2>\ngetlogin<\/b>() 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<\/b>().<\/p>\n
getlogin_r<\/b>() returns this same username in the array buf<\/i> of size bufsize<\/i>.<\/p>\n
cuserid<\/b>() returns a pointer to a string containing a username associated with the effective user ID of the process. If string<\/i> is not a null pointer, it should be an array that can hold at least L_cuserid<\/b> 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<\/b>().<\/p>\n
The macro L_cuserid<\/b> is an integer constant that indicates how long an array you might need to store a username. L_cuserid<\/b> is declared in <\/i>.<\/p>\nThese functions let your program identify positively the user who is running (cuserid<\/b>()) or the user who logged in this session (getlogin<\/b>()). (These can differ when set-user-ID programs are involved.)<\/p>\n
For most purposes, it is more useful to use the environment variable LOGNAME<\/b> to find out who the user is. This is more flexible precisely because the user can set LOGNAME<\/b> arbitrarily.<\/p>\nRETURN VALUE <\/a> <\/h2>\ngetlogin<\/b>() returns a pointer to the username when successful, and NULL on failure, with errno<\/i> set to indicate the cause of the error. getlogin_r<\/b>() returns 0 when successful, and nonzero on failure.<\/p>\nERRORS <\/a> <\/h2>\nPOSIX specifies:<\/p>\n
#include char *getlogin(void); #include char *cuserid(char *<\/b>string<\/i>);<\/b><\/p>\n Feature Test Macro Requirements for glibc (see feature_test_macros<\/b>(7)):<\/p>\n getlogin_r<\/b>(): _POSIX_C_SOURCE\u00a0>=\u00a0199506L<\/p>\n cuserid<\/b>(): getlogin<\/b>() 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<\/b>().<\/p>\n getlogin_r<\/b>() returns this same username in the array buf<\/i> of size bufsize<\/i>.<\/p>\n cuserid<\/b>() returns a pointer to a string containing a username associated with the effective user ID of the process. If string<\/i> is not a null pointer, it should be an array that can hold at least L_cuserid<\/b> 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<\/b>().<\/p>\n The macro L_cuserid<\/b> is an integer constant that indicates how long an array you might need to store a username. L_cuserid<\/b> is declared in These functions let your program identify positively the user who is running (cuserid<\/b>()) or the user who logged in this session (getlogin<\/b>()). (These can differ when set-user-ID programs are involved.)<\/p>\n For most purposes, it is more useful to use the environment variable LOGNAME<\/b> to find out who the user is. This is more flexible precisely because the user can set LOGNAME<\/b> arbitrarily.<\/p>\n getlogin<\/b>() returns a pointer to the username when successful, and NULL on failure, with errno<\/i> set to indicate the cause of the error. getlogin_r<\/b>() returns 0 when successful, and nonzero on failure.<\/p>\n POSIX specifies:<\/p>\n
int getlogin_r(char *<\/b>buf<\/i>, size_t<\/b> bufsize<\/i>);<\/b><\/p>\n
Since glibc 2.24:
(_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
|| _GNU_SOURCE
Up to and including glibc 2.23:
_XOPEN_SOURCE<\/p>\nDESCRIPTION <\/a> <\/h2>\n
RETURN VALUE <\/a> <\/h2>\n
ERRORS <\/a> <\/h2>\n
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