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Rmoved some crufty text; ffixes;

This commit is contained in:
Michael Kerrisk 2008-06-29 07:01:28 +00:00
parent 5018c1b4c5
commit 377dda5900
1 changed files with 20 additions and 19 deletions
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39
man5/utmp.5
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@ -55,20 +55,20 @@ around; details depend on the version of libc):
.sp
/* Values for ut_type field, below */
#define EMPTY 0 /* Record does not contain valid info
(formerly known as UT_UNKNOWN) */
#define RUN_LVL 1 /* Change in system run-level (see
\fBinit\fP(8) */
#define BOOT_TIME 2 /* Time of system booy (in \fIut_tv\fP) */
#define NEW_TIME 3 /* Time after system clock change
(in \fIut_tv\fP) */
#define OLD_TIME 4 /* Time before system clock change
(in \fIut_tv\fP) */
#define INIT_PROCESS 5 /* Process spawned by \fBinit\fP(8) */
#define LOGIN_PROCESS 6 /* Session leader process for user login */
#define USER_PROCESS 7 /* Normal process */
#define DEAD_PROCESS 8 /* Terminated process */
#define ACCOUNTING 9 /* Not implemented */
#define EMPTY 0 /* Record does not contain valid info
(formerly known as UT_UNKNOWN on Linux) */
#define RUN_LVL 1 /* Change in system run-level (see
\fBinit\fP(8) */
#define BOOT_TIME 2 /* Time of system booy (in \fIut_tv\fP) */
#define NEW_TIME 3 /* Time after system clock change
(in \fIut_tv\fP) */
#define OLD_TIME 4 /* Time before system clock change
(in \fIut_tv\fP) */
#define INIT_PROCESS 5 /* Process spawned by \fBinit\fP(8) */
#define LOGIN_PROCESS 6 /* Session leader process for user login */
#define USER_PROCESS 7 /* Normal process */
#define DEAD_PROCESS 8 /* Terminated process */
#define ACCOUNTING 9 /* Not implemented */
#define UT_LINESIZE 32
#define UT_NAMESIZE 32
@ -246,28 +246,29 @@ structure.
.SS Comparison with Historical Systems
Linux utmp entries conform neither to v7/BSD nor to System V; they are a
mix of the two.
v7/BSD has fewer fields; most importantly it lacks
\fIut_type\fP, which causes native v7/BSD-like programs to display (for
example) dead or login entries.
Further, there is no configuration file
which allocates slots to sessions.
BSD does so because it lacks \fIut_id\fP fields.
In Linux (as in System V), the \fIut_id\fP field of a
record will never change once it has been set, which reserves that slot
without needing a configuration file.
Clearing \fIut_id\fP may result
in race conditions leading to corrupted utmp entries and potential
security holes.
Clearing the above mentioned fields by filling them
Clearing the abovementioned fields by filling them
with null bytes is not required by System V semantics,
but makes it possible to run
many programs which assume BSD semantics and which do not modify utmp.
Linux uses the BSD conventions for line contents, as documented above.
.PP
System V only uses the type field to mark them and logs informative messages
such as \fB"new time"\fP in the line field.
\fBUT_UNKNOWN\fP seems
to be a Linux invention.
.\" mtk: What is the referrent of "them" in the following sentence?
.\" System V only uses the type field to mark them and logs
.\" informative messages such as \fB"new time"\fP in the line field.
System V has no \fIut_host\fP or \fIut_addr_v6\fP fields.
.SH NOTES
.PP