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



NAME
       setaliasent, endaliasent, getaliasent, getaliasent_r, getaliasbyname, getaliasbyname_r - read an alias entry

SYNOPSIS
       #include <aliases.h>

       void setaliasent(void);

       void endaliasent(void);

       struct aliasent *getaliasent(void);

       int getaliasent_r(struct aliasent *result,
               char *buffer, size_t buflen, struct aliasent **res);

       struct aliasent *getaliasbyname(const char *name);

       int getaliasbyname_r(const char *name, struct aliasent *result,
               char *buffer, size_t buflen, struct aliasent **res);

DESCRIPTION
       One  of  the databases available with the Name Service Switch (NSS) is the aliases database, that contains mail
       aliases.  (To find out which databases are supported, try  getent  --help.)   Six  functions  are  provided  to
       access the aliases database.

       The  getaliasent()  function returns a pointer to a structure containing the group information from the aliases
       database.  The first time it is called it returns the first entry; thereafter, it returns successive entries.

       The setaliasent() function rewinds the file pointer to the beginning of the aliases database.

       The endaliasent() function closes the aliases database.

       getaliasent_r() is the reentrant version of the previous function.  The requested structure is stored  via  the
       first  argument  but  the programmer needs to fill the other arguments also.  Not providing enough space causes
       the function to fail.

       The function getaliasbyname() takes the name argument and searches the aliases database.  The entry is returned
       as a pointer to a struct aliasent.

       getaliasbyname_r()  is  the  reentrant version of the previous function.  The requested structure is stored via
       the second argument but the programmer needs to fill the other arguments  also.   Not  providing  enough  space
       causes the function to fail.

       The struct aliasent is defined in <aliases.h>:

           struct aliasent {
               char    *alias_name;             /* alias name */
               size_t   alias_members_len;
               char   **alias_members;          /* alias name list */
               int      alias_local;
           };

RETURN VALUE
       The functions getaliasent_r() and getaliasbyname_r() return a non-zero value on error.

FILES
       The default alias database is the file /etc/aliases.  This can be changed in the /etc/nsswitch.conf file.

CONFORMING TO
       These routines are glibc-specific.  The NeXT has similar routines:

           #include <aliasdb.h>

           void alias_setent(void);
           void alias_endent(void);
           alias_ent *alias_getent(void);
           alias_ent *alias_getbyname(char *name);

EXAMPLE
       The following example compiles with gcc example.c -o example.  It will dump all names in the alias database.

       #include <aliases.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <errno.h>

       int
       main(void)
       {
           struct aliasent *al;
           setaliasent();
           for (;;) {
               al = getaliasent();
               if (al == NULL)
                   break;
               printf("Name: %s\n", al->alias_name);
           }
           if (errno) {
               perror("reading alias");
               exit(EXIT_FAILURE);
           }
           endaliasent();
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       getgrent(3), getpwent(3), getspent(3), aliases(5)

COLOPHON
       This  page  is part of release 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                               2003-09-09                    SETALIASENT(3)