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NAME

       getspnam,   getspnam_r,   getspent,   getspent_r,  setspent,  endspent,
       fgetspent,  fgetspent_r,  sgetspent,  sgetspent_r,  putspent,  lckpwdf,
       ulckpwdf - get shadow password file entry

SYNOPSIS

       /* General shadow password file API */
       #include <shadow.h>

       struct spwd *getspnam(const char *name);

       struct spwd *getspent(void);

       void setspent(void);

       void endspent(void);

       struct spwd *fgetspent(FILE *fp);

       struct spwd *sgetspent(const char *s);

       int putspent(struct spwd *p, FILE *fp);

       int lckpwdf(void);

       int ulckpwdf(void);

       /* GNU extension */
       #include <shadow.h>

       int getspent_r(struct spwd *spbuf,
               char *buf, size_t buflen, struct spwd **spbufp);

       int getspnam_r(const char *name, struct spwd *spbuf,
               char *buf, size_t buflen, struct spwd **spbufp);

       int fgetspent_r(FILE *fp, struct spwd *spbuf,
               char *buf, size_t buflen, struct spwd **spbufp);

       int sgetspent_r(const char *s, struct spwd *spbuf,
               char *buf, size_t buflen, struct spwd **spbufp);

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

       getspent_r(), getspnam_r(), fgetspent_r(), sgetspent_r(): _BSD_SOURCE
       || _SVID_SOURCE

DESCRIPTION

       Long ago it was considered safe  to  have  encrypted  passwords  openly
       visible in the password file.  When computers got faster and people got
       more security-conscious,  this  was  no  longer  acceptable.   Julianne
       Frances  Haugh  implemented  the  shadow  password suite that keeps the
       encrypted passwords in the shadow password database  (e.g.,  the  local
       shadow  password  file  /etc/shadow,  NIS,  and LDAP), readable only by
       root.

       The functions  described  below  resemble  those  for  the  traditional
       password database (e.g., see getpwnam(3) and getpwent(3)).

       The getspnam() function returns a pointer to a structure containing the
       broken-out fields of the record in the shadow  password  database  that
       matches the user name name.

       The  getspent()  function  returns  a  pointer to the next entry in the
       shadow  password  database.   The  position  in  the  input  stream  is
       initialized  by  setspent().   When  done reading, the program may call
       endspent() so that resources can be deallocated.

       The fgetspent() function is similar to getspent() but uses the supplied
       stream instead of the one implicitly opened by setspent().

       The  sgetspent()  function  parses  the supplied string s into a struct
       spwd.

       The putspent() function writes the contents of the supplied struct spwd
       *p  as a text line in the shadow password file format to the stream fp.
       String entries with value NULL and numerical entries with value -1  are
       written as an empty string.

       The   lckpwdf()  function  is  intended  to  protect  against  multiple
       simultaneous accesses of the shadow password  database.   It  tries  to
       acquire  a  lock,  and returns 0 on success, or -1 on failure (lock not
       obtained within 15 seconds).  The ulckpwdf() function releases the lock
       again.   Note  that there is no protection against direct access of the
       shadow password file.  Only programs that use lckpwdf() will notice the
       lock.

       These were the functions that formed the original shadow API.  They are
       widely available.

   Reentrant versions
       Analogous to the reentrant functions for the password  database,  glibc
       also  has  reentrant  functions  for the shadow password database.  The
       getspnam_r() function is  like  getspnam()  but  stores  the  retrieved
       shadow  password  structure  in  the  space  pointed to by spbuf.  This
       shadow password structure  contains  pointers  to  strings,  and  these
       strings  are stored in the buffer buf of size buflen.  A pointer to the
       result (in case of success) or NULL (in case no entry was found  or  an
       error occurred) is stored in *spbufp.

       The   functions  getspent_r(),  fgetspent_r(),  and  sgetspent_r()  are
       similarly analogous to their non-reentrant counterparts.

       Some non-glibc systems also have functions with these names, often with
       different prototypes.

   Structure
       The shadow password structure is defined in <shadow.h> as follows:

           struct spwd {
               char *sp_namp;         /* Login name */
               char *sp_pwdp;         /* Encrypted password */
               long  sp_lstchg;       /* Date of last change */
               long  sp_min;          /* Min #days between changes */
               long  sp_max;          /* Max #days between changes */
               long  sp_warn;         /* #days before pwd expires
                                         to warn user to change it */
               long  sp_inact;        /* #days after pwd expires
                                         until account is disabled */
               long  sp_expire;       /* #days since 1970-01-01
                                         until account is disabled */
               unsigned long sp_flag; /* Reserved */
           };

RETURN VALUE

       The  functions that return a pointer return NULL if no more entries are
       available or if an error occurs during processing.  The functions which
       have int as the return value return 0 for success and -1 for failure.

       For  the  non-reentrant functions, the return value may point to static
       area, and may be overwritten by subsequent calls to these functions.

       The reentrant functions return zero on success.  In case of  error,  an
       error number is returned.

ERRORS

       ERANGE Supplied buffer is too small.

FILES

       /etc/shadow
              local shadow password database file

       /etc/.pwd.lock
              lock file

       The  include  file  <paths.h>  defines the constant _PATH_SHADOW to the
       pathname of the shadow password file.

CONFORMING TO

       The shadow password database and its associated API are  not  specified
       in POSIX.1-2001.  However, many other systems provide a similar API.

SEE ALSO

       getgrnam(3), getpwnam(3), getpwnam_r(3), shadow(5)

COLOPHON

       This  page  is  part of release 2.77 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/.