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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<refentry id= "sd_journal_next" >
<refentryinfo >
<title > sd_journal_next</title>
<productname > systemd</productname>
<authorgroup >
<author >
<contrib > Developer</contrib>
<firstname > Lennart</firstname>
<surname > Poettering</surname>
<email > lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta >
<refentrytitle > sd_journal_next</refentrytitle>
<manvolnum > 3</manvolnum>
</refmeta>
<refnamediv >
<refname > sd_journal_next</refname>
<refname > sd_journal_previous</refname>
<refname > sd_journal_next_skip</refname>
<refname > sd_journal_previous_skip</refname>
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<refname > SD_JOURNAL_FOREACH</refname>
<refname > SD_JOURNAL_FOREACH_BACKWARDS</refname>
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<refpurpose > Advance or set back the read pointer in the journal</refpurpose>
</refnamediv>
<refsynopsisdiv >
<funcsynopsis >
<funcsynopsisinfo > #include < systemd/sd-journal.h> </funcsynopsisinfo>
<funcprototype >
<funcdef > int <function > sd_journal_next</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
</funcprototype>
<funcprototype >
<funcdef > int <function > sd_journal_previous</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
</funcprototype>
<funcprototype >
<funcdef > int <function > sd_journal_next_skip</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
<paramdef > uint64_t <parameter > skip</parameter> </paramdef>
</funcprototype>
<funcprototype >
<funcdef > int <function > sd_journal_previous_skip</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
<paramdef > uint64_t <parameter > skip</parameter> </paramdef>
</funcprototype>
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<funcprototype >
<funcdef > <function > SD_JOURNAL_FOREACH</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
</funcprototype>
<funcprototype >
<funcdef > <function > SD_JOURNAL_FOREACH_BACKWARDS</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
</funcprototype>
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</funcsynopsis>
</refsynopsisdiv>
<refsect1 >
<title > Description</title>
<para > <function > sd_journal_next()</function> advances
the read pointer into the journal by one entry. The
only argument taken is a journal context object as
allocated via
<citerefentry > <refentrytitle > sd_journal_open</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> . After
successful invocation the entry may be read with
functions such as
<citerefentry > <refentrytitle > sd_journal_get_data</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> .</para>
<para > Similar, <function > sd_journal_previous()</function> sets
the read pointer back one entry.</para>
<para > <function > sd_journal_next_skip()</function> and
<function > sd_journal_previous_skip()</function>
advance/set back the read pointer by multiple entries
at once, as specified in the <varname > skip</varname>
parameter.</para>
<para > The journal is strictly ordered by reception
time, and hence advancing to the next entry guarantees
that the entry then pointing to is later in time than
then previous one, or has the same timestamp.</para>
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<para > Note that
<citerefentry > <refentrytitle > sd_journal_get_data</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
and related calls will fail unless
<function > sd_journal_next()</function> has been
invoked at least once in order to position the read
pointer on a journal entry.</para>
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<para > Note that the
<function > SD_JOURNAL_FOREACH()</function> macro may be used
as a wrapper around
<citerefentry > <refentrytitle > sd_journal_seek_head</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
and <function > sd_journal_next()</function> in order to
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make iterating through the journal easier. See below
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for an example. Similar,
<function > SD_JOURNAL_FOREACH_BACKWARDS()</function>
may be used for iterating the journal in reverse
order.</para>
</refsect1>
<refsect1 >
<title > Return Value</title>
<para > The four calls return the number of entries
advanced/set back on success or a negative errno-style
Reword sentences that contain psuedo-English "resp."
As you likely know, Arch Linux is in the process of moving to systemd.
So I was reading through the various systemd docs and quickly became
baffled by this new abbreviation "resp.", which I've never seen before
in my English-mother-tongue life.
Some quick Googling turned up a reference:
<http://www.transblawg.eu/index.php?/archives/870-Resp.-and-other-non-existent-English-wordsNicht-existente-englische-Woerter.html>
I guess it's a literal translation of the German "Beziehungsweise", but
English doesn't work the same way. The word "respectively" is used
exclusively to provide an ordering connection between two lists. E.g.
"the prefixes k, M, and G refer to kilo-, mega-, and giga-,
respectively." It is also never abbreviated to "resp." So the sentence
"Sets the default output resp. error output for all services and
sockets" makes no sense to a natural English speaker.
This patch removes all instances of "resp." in the man pages and
replaces them with sentences which are much more clear and, hopefully,
grammatically valid. In almost all instances, it was simply replacing
"resp." with "or," which the original author (Lennart?) could probably
just do in the future.
The only other instances of "resp." are in the src/ subtree, which I
don't feel privileged to correct.
Signed-off-by: Andrew Eikum <aeikum@codeweavers.com>
2012-10-15 22:59:12 +04:00
error code. When the end or beginning of the journal
is reached, a number smaller than requested is
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returned. More specifically, if
<function > sd_journal_next()</function> or
<function > sd_journal_previous()</function> reach the
end/beginning of the journal they will return 0,
instead of 1 when they are successful. This should be
considered an EOF marker.</para>
</refsect1>
<refsect1 >
<title > Notes</title>
<para > The <function > sd_journal_next()</function> , <function > sd_journal_previous()</function> ,
<function > sd_journal_next_skip()</function> and
<function > sd_journal_previous_skip()</function> interfaces are
available as shared library, which can be compiled and
linked to with the
<literal > libsystemd-journal</literal>
<citerefentry > <refentrytitle > pkg-config</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry>
file.</para>
</refsect1>
<refsect1 >
<title > Examples</title>
<para > Iterating through the journal:</para>
<programlisting > #include < stdio.h>
#include < string.h>
#include < systemd/sd-journal.h>
int main(int argc, char *argv[]) {
int r;
sd_journal *j;
r = sd_journal_open(& j, SD_JOURNAL_LOCAL_ONLY);
if (r < 0) {
fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
return 1;
}
SD_JOURNAL_FOREACH(j) {
const char *d;
size_t l;
r = sd_journal_get_data(j, "MESSAGE", & d, & l);
if (r < 0) {
fprintf(stderr, "Failed to read message field: %s\n", strerror(-r));
continue;
}
printf("%.*s\n", (int) l, d);
}
sd_journal_close(j);
return 0;
}</programlisting>
</refsect1>
<refsect1 >
<title > See Also</title>
<para >
<citerefentry > <refentrytitle > systemd</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd-journal</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd_journal_open</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> ,
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<citerefentry > <refentrytitle > sd_journal_get_data</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd_journal_get_realtime_usec</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd_journal_get_cursor</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
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</para>
</refsect1>
</refentry>
