endutxent, getutxent, getutxid, getutxline, pututxline,
setutxent - Access user accounting database functions
#include <utmpx.h>
void endutxent(
void ); struct utmpx *getutxent(
void ); struct utmpx *getutxid(
const struct utmpx *id ); struct utmpx *getutxline(
const struct utmpx *line ); struct utmpx *pututxline(
const struct utmpx *utmpx ); void setutxent(
void );
Standard C Library (libc)
Interfaces documented on this reference page conform to
industry standards as follows:
endutxent(), getutxent(), getutxid(), getutxline(),
pututxline(), setutxent(): XPG4-UNIX
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Specifies one of the BOOT_TIME, OLD_TIME, NEW_TIME,
INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS
entries. Matches a utmpx entry of the type LOGIN_PROCESS
or USER_PROCESS such that the ut_line member matches
line->ut_line. Points to a utmpx structure to be placed
into the user accounting database.
These functions provide access to the user accounting
database.
The getutxent() function reads the next entry from the
user accounting database. If the database is not already
open, getutxent() opens it. If the end of the database is
reached, getutxent fails.
The getutxid() function searches forward from the current
point in the database. If the ut_type value of the utmpx
structure pointed to by the id parameter is BOOT_TIME,
OLD_TIME, or NEW_TIME, the getutxid() function stops when
an entry with a matching ut_type value is found.
If the ut_type value is INIT_PROCESS, LOGIN_PROCESS,
USER_PROCESS, or DEAD_PROCESS, the getutxid() function
returns a pointer to the first entry whose type is one of
these four and whose ut_id field matches id->ut_id. If the
end of the database is reached without a match, the
getutxid() function fails.
The getutxline() function searches forward from the current
point in the database until it finds an entry of the
type LOGIN_PROCESS or USER_PROCESS which also has a
ut_line value that matches the value in the utmpx structure
pointed to by the line parameter. If the end of the
database is reached without a match, the getutxline()
function fails.
If the process has appropriate privileges, the pututxline()
function writes out the structure into the user
accounting database. The pututxline() function calls
getutxid() to search for a record that satisfies the
request. If this search succeeds, the entry is replaced.
Otherwise, a new entry is made at the end of the user
accounting database.
The setutxent() function resets the input stream to the
beginning of the database. This should be done before each
search for a new entry if you want to examine the entire
database.
The endutxent() function closes the user accounting
database.
The most current entry is saved in a thread-specific
structure, which is overwritten by a subsequent call to
getutxid() or getutxline() by the same thread. To make
multiple accesses, you must copy or use the structure
between each access. The getutxid() and getutxline() functions
examine the thread-specific structure first. If the
contents of this structure match what they are searching
for, they do not read the database. Therefore, you must
fill the thread-specific structure with zeros after each
use if you want to use these subroutines to search for
multiple occurrences.
If the pututxline() function finds that it is not already
at the correct place in the user accounting database, the
implicit read it performs does not overwrite the contents
of the thread-specific structure returned by the getutxent(),
getutxid(), or getutxline() functions. This allows
you to get an entry with one of these subroutines, modify
the structure, and pass the pointer back to the pututxline()
function for writing.
These functions use buffered standard I/O for input, but
the pututxline() function uses an unbuffered write to
avoid race conditions between processes trying to modify
the utmpx and wtmpx files.
Upon successful completion, the getutxent(), getutxid(),
and getutxline() functions return pointers to a utmpx
structure containing a copy of the requested entry in the
user accounting database. Otherwise, a null pointer is
returned.
Upon successful completion, the pututxline() function
returns a pointer to a utmpx structure containing a copy
of the entry added to the user accounting database. Otherwise,
a null pointer is returned.
The pututxline() function may fail and set errno to the
corresponding value if the following condition occurs: The
process does not have the appropriate privileges.
Accounting header file that defines the format for the
login database file. The active login/logoff database
files.
Standards: standards(5)
getutxent(3)
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