mirror of https://github.com/mkerrisk/man-pages
150 lines
3.6 KiB
Groff
150 lines
3.6 KiB
Groff
.\" Copyright 2003 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
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.\" Distributed under GPL
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.\"
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.\" Polished a bit, added a little, aeb
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.\"
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.TH SETALIASENT 3 2003-09-09 "GNU" "Linux Programmer's Manual"
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.SH NAME
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setaliasent, endaliasent, getaliasent, getaliasent_r,
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getaliasbyname, getaliasbyname_r \- read an alias entry
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.SH SYNOPSIS
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.B #include <aliases.h>
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.sp
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.B "void setaliasent(void);"
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.sp
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.B "void endaliasent(void);"
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.sp
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.B "struct aliasent *getaliasent(void);"
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.sp
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.BI "int getaliasent_r(struct aliasent *" result ","
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.br
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.BI " char *" buffer ", size_t " buflen ", struct aliasent **" res );
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.sp
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.BI "struct aliasent *getaliasbyname(const char *" name );
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.sp
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.BI "int getaliasbyname_r(const char *" name ", struct aliasent *" result ,
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.br
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.BI " char *" buffer ", size_t " buflen ", struct aliasent **" res );
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.SH DESCRIPTION
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One of the databases available with the Name Service Switch (NSS)
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is the aliases database, that contains mail aliases.
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(To find out which databases are supported, try \fIgetent \-\-help\fP.)
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Six functions are provided to access the aliases database.
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.PP
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The
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.BR getaliasent ()
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function returns a pointer to a structure containing
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the group information from the aliases database.
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The first time it is called it returns the first entry;
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thereafter, it returns successive entries.
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.PP
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The
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.BR setaliasent ()
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function rewinds the file pointer to the beginning of the
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aliases database.
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.PP
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The
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.BR endaliasent ()
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function closes the aliases database.
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.PP
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.BR getaliasent_r ()
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is the reentrant version of the previous function.
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The requested structure
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is stored via the first argument but the programmer needs to fill the other
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arguments also.
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Not providing enough space causes the function to fail.
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.PP
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The function
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.BR getaliasbyname ()
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takes the name argument and searches the aliases database.
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The entry is returned as a pointer to a
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.IR "struct aliasent" .
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.PP
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.BR getaliasbyname_r ()
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is the reentrant version of the previous function.
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The requested structure
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is stored via the second argument but the programmer needs to fill the other
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arguments also.
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Not providing enough space causes the function to fail.
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.PP
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The
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.I "struct aliasent"
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is defined in
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.IR <aliases.h> :
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.in +4n
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.nf
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struct aliasent {
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char *alias_name; /* alias name */
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size_t alias_members_len;
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char **alias_members; /* alias name list */
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int alias_local;
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};
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.fi
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.in
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.SH "RETURN VALUE"
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The functions
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.BR getaliasent_r ()
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and
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.BR getaliasbyname_r ()
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return a non-zero value on error.
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.SH FILES
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The default alias database is the file
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.IR /etc/aliases .
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This can be changed in the
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.I /etc/nsswitch.conf
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file.
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.SH "CONFORMING TO"
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These routines are glibc-specific.
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The NeXT has similar routines:
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.in +4n
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.nf
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#include <aliasdb.h>
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void alias_setent(void);
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void alias_endent(void);
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alias_ent *alias_getent(void);
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alias_ent *alias_getbyname(char *name);
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.fi
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.in
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.SH EXAMPLE
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The following example compiles with
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.IR "gcc example.c \-o example" .
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It will dump all names in the alias database.
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.sp
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.nf
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#include <aliases.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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int
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main(void)
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{
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struct aliasent *al;
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setaliasent();
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for (;;) {
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al = getaliasent();
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if (al == NULL)
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break;
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printf("Name: %s\\n", al\->alias_name);
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}
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if (errno) {
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perror("reading alias");
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exit(EXIT_FAILURE);
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}
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endaliasent();
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exit(EXIT_SUCCESS);
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}
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.fi
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.SH "SEE ALSO"
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.BR getgrent (3),
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.BR getpwent (3),
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.BR getspent (3),
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.BR aliases (5)
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.\"
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.\" /etc/sendmail/aliases
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.\" Yellow Pages
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.\" newaliases, postalias
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