getpass (3)
Leading comments
Copyright (c) 2000 Andries Brouwer (aeb@cwi.nl) %%%LICENSE_START(GPLv2+_DOC_FULL) This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The GNU General Public License's references to "object code" and "executables" are to be interpreted as the output of any document formatting or typesetting system, including i...
NAME
getpass - get a passwordSYNOPSIS
#include <unistd.h>char *getpass(const char *prompt);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getpass():
-
- Since glibc 2.2.2:
-
_BSD_SOURCE || (_XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) && !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) - Before glibc 2.2.2:
- none
DESCRIPTION
This function is obsolete. Do not use it. If you want to read input without terminal echoing enabled, see the description of the ECHO flag in termios(3).The getpass() function opens /dev/tty (the controlling terminal of the process), outputs the string prompt, turns off echoing, reads one line (the "password"), restores the terminal state and closes /dev/tty again.
RETURN VALUE
The function getpass() returns a pointer to a static buffer containing (the first PASS_MAX bytes of) the password without the trailing newline, terminated by a null byte (aq\0aq). This buffer may be overwritten by a following call. On error, the terminal state is restored, errno is set appropriately, and NULL is returned.ERRORS
The function may fail if- ENXIO
- The process does not have a controlling terminal.
FILES
/dev/ttyATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).| Interface | Attribute | Value |
| getpass() | Thread safety | MT-Unsafe term |
CONFORMING TO
Present in SUSv2, but marked LEGACY. Removed in POSIX.1-2001.NOTES
In the GNU C library implementation, if /dev/tty cannot be opened, the prompt is written to stderr and the password is read from stdin. There is no limit on the length of the password. Line editing is not disabled.
According to SUSv2, the value of PASS_MAX must be defined in <limits.h> in case it is smaller than 8, and can in any case be obtained using sysconf(_SC_PASS_MAX). However, POSIX.2 withdraws the constants PASS_MAX and _SC_PASS_MAX, and the function getpass(). The glibc version accepts _SC_PASS_MAX and returns BUFSIZ (e.g., 8192).