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 <= 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       This function is obsolete.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 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 to indicate the error, and NULL is
       returned.

ERRORS
       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 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)

Linux                                                                          2021-03-22                                                                     GETPASS(3)