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Linux Programmer's Manual (3)
getpass - get a password
char *getpass( const char *prompt);
Feature Test Macro Requirements for glibc (see
- Since glibc 2.2.2:
(_XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
!(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
- Before glibc 2.2.2:
This function is obsolete.
Do not use it.
If you want to read input without terminal echoing enabled,
see the description of the
(the controlling terminal of the process), outputs the string
turns off echoing, reads one line (the "password"),
restores the terminal state and closes
returns a pointer to a static buffer containing (the first
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,
is set appropriately, and NULL is returned.
The function may fail if
The process does not have a controlling terminal.
Multithreading (see pthreads(7))
function is not thread-safe.
Present in SUSv2, but marked LEGACY.
Removed in POSIX.1-2001.
For libc4 and libc5, the prompt is not written to
cannot be opened, the password is read from
The static buffer has length 128 so that only the first 127
bytes of the password are returned.
While reading the password, signal generation
is disabled and the corresponding characters
(usually control-C, control-\, control-Z and control-Y)
are transmitted as part of the password.
Since libc 5.4.19 also line editing is disabled, so that also
backspace and the like will be seen as part of the password.
For glibc2, if
cannot be opened, the prompt is written to
and the password is read from
There is no limit on the length of the password.
Line editing is not disabled.
According to the SUSv2, the value of
must be defined in
in case it is smaller than 8, and can in any case be obtained using
However, POSIX.2 withdraws the constants
and the function
Libc4 and libc5 have never supported
The calling process should zero the password as soon as possible to avoid
leaving the cleartext password visible in the process's address space.
This page is part of release 3.66 of the Linux
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
- RETURN VALUE
- Multithreading (see pthreads(7))
- CONFORMING TO
- SEE ALSO
This document was created by
using the manual pages.
Time: 21:43:00 GMT, July 12, 2014