getpass

GETPASS(3)                 Linux Programmer's Manual                GETPASS(3)

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       This  function  is obsolete.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 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 new-
       line, 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.

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).

       +----------+---------------+----------------+
       |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 dis-
       abled.

       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 ver-
       sion 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
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       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)
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