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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:
               _BSD_SOURCE ||
                   (_XOPEN_SOURCE >= 500 ||
                       _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
                   !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
           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       This  function  is obsolete.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
   Multithreading (see pthreads(7))
       The getpass() function is not thread-safe.
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  <lim-
       its.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 3.53 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                             2013-06-21                        GETPASS(3)