Man Linux: Main Page and Category List


       getpass - get a password


       #include <unistd.h>

       char *getpass( const char *prompt);


       This function is obsolete.  Do not use it.

       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


       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.


       The function may fail if

       ENXIO  The process does not have a controlling terminal.




       Present in SUSv2, but marked LEGACY.  Removed in POSIX.1-2001.


       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, SIGTSTOP) 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
       <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().  Libc4
       and libc5  have  never  supported  PASS_MAX  or  _SC_PASS_MAX.   Glibc2
       accepts _SC_PASS_MAX and returns BUFSIZ (e.g., 8192).


       The  calling  process  should  zero the password as soon as possible to
       avoid leaving the cleartext password visible in the  process’s  address




       This  page  is  part of release 3.24 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at