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

NAME
       getpass - get a password

SYNOPSIS
       #include 

       char *getpass( const char *prompt);

   Feature Test Macro Requirements for glibc (see featuretestmacros(7)):

       getpass():
           Since glibc 2.2.2:
               BSDSOURCE ||
                   (XOPENSOURCE >= 500 ||
                       XOPENSOURCE && XOPENSOURCEEXTENDED) &&
                   !(POSIXCSOURCE >= 200112L || XOPENSOURCE >= 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       This  function  is obsolete.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  PASSMAX  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
       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 PASSMAX must be defined in  in case it is smaller than 8, and can in any  case  be  obtained
       using  sysconf(SCPASSMAX).  However, POSIX.2 withdraws the constants
       PASSMAX and SCPASSMAX, and the function getpass().  Libc4 and libc5
       have   never   supported  PASSMAX  or  SCPASSMAX.   Glibc2  accepts
       SCPASSMAX 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)