GETPASS(3) BSD Library Functions Manual GETPASS(3)NAME
getpass -- get a password
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <pwd.h>
#include <unistd.h>
char *
getpass(const char *prompt);
DESCRIPTION
The getpass() function displays a prompt to, and reads in a password from, /dev/tty. If this file is not accessible, getpass() displays the
prompt on the standard error output and reads from the standard input.
The password may be up to _PASSWORD_LEN (currently 128) characters in length. Any additional characters and the terminating newline charac-
ter are discarded.
getpass() turns off character echoing while reading the password.
RETURN VALUES
getpass() returns a pointer to the null terminated password.
FILES
/dev/tty
SEE ALSO crypt(3)STANDARDS
The getpass() function appeared in Version 2 of the Single UNIX Specification (``SUSv2''), but it was already marked as legacy. The function
was removed in the IEEE Std 1003.1-2001 (``POSIX.1'') standard.
HISTORY
A getpass() function appeared in Version 7 AT&T UNIX.
BUGS
The getpass() function leaves its result in an internal static object and returns a pointer to that object. Subsequent calls to getpass()
will modify the same object.
SECURITY CONSIDERATIONS
The calling process should zero the password as soon as possible to avoid leaving the cleartext password visible in the process's address
space.
BSD May 6, 2010 BSD
Check Out this Related Man Page
GETPASS(3) Linux Programmer's Manual GETPASS(3)NAME
getpass - get a password
SYNOPSIS
#include <unistd.h>
char *getpass( const char *prompt);
DESCRIPTION
This function is obsolete. Do not use it.
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 new-
line, terminated by a null byte (' '). 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/tty
CONFORMING TO
Present in SUSv2, but marked LEGACY. Removed in POSIX.1-2001.
NOTES
For libc4 and libc5, the prompt is not written to /dev/tty but to stderr. Moreover, if /dev/tty cannot be opened, the password is read
from stdin. The static buffer has length 128 so that only the first 127 bytes of the password are returned. While reading the password,
signal generation (SIGINT, SIGQUIT, SIGSTOP, SIGTSTP) 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 /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 the 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(). Libc4 and
libc5 have never supported PASS_MAX or _SC_PASS_MAX. Glibc2 accepts _SC_PASS_MAX and 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)COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2000-12-05 GETPASS(3)