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       This  function  is  obsolete.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 termi‐
       nal 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 newline, 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
       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 disabled.

       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 version 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 3.74 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2014-08-19                                 GETPASS(3)