Manpage of GETPASS

GETPASS

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

NAME

getpass - get a password  

SYNOPSIS

#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
 

DESCRIPTION

This function is obsolete. Do not use it. If you want to read input without terminal echoing enabled, see the description of the ECHOflag 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/ttyagain.  

RETURN VALUE

The function getpass() returns a pointer to a static buffer containing (the first PASS_MAXbytes 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, errnois set appropriately, and NULL is returned.  

ERRORS

The function may fail if
ENXIO
The process does not have a controlling terminal.
 

FILES

/dev/tty 

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
getpass() Thread safetyMT-Unsafe term
 

CONFORMING TO

Present in SUSv2, but marked LEGACY. Removed in POSIX.1-2001.  

NOTES

In the GNU C library implementation, if /dev/ttycannot be opened, the prompt is written to stderrand 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_MAXmust 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_MAXand _SC_PASS_MAX, and the function getpass(). The glibc version accepts _SC_PASS_MAXand returns BUFSIZ(e.g., 8192).  

BUGS

The calling process should zero the password as soon as possible to avoid leaving the cleartext password visible in the process's address space.  

SEE ALSO

crypt(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
FILES
ATTRIBUTES
CONFORMING TO
NOTES
BUGS
SEE ALSO

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Time: 22:27:55 GMT, June 20, 2016