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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | FILES | ATTRIBUTES | CONFORMING TO | NOTES | BUGS | SEE ALSO | COLOPHON |
GETPASS(3) Linux Programmer's Manual GETPASS(3)
getpass - get a password
#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:
_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
Before glibc 2.2.2:
none
This function is obsolete.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.
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 ('\0'). This buffer may
be overwritten by a following call. On error, the terminal state is
restored, errno is set appropriately, and NULL is returned.
The function may fail if
ENXIO The process does not have a controlling terminal.
/dev/tty
For an explanation of the terms used in this section, see
attributes(7).
┌──────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├──────────┼───────────────┼────────────────┤
│getpass() │ Thread safety │ MT-Unsafe term │
└──────────┴───────────────┴────────────────┘
Present in SUSv2, but marked LEGACY. Removed in POSIX.1-2001.
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).
The calling process should zero the password as soon as possible to
avoid leaving the cleartext password visible in the process's address
space.
crypt(3)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2016-03-15 GETPASS(3)
Pages that refer to this page: crypt(3)