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Diffstat (limited to 'man/sd_journal_query_unique.xml')
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1 files changed, 172 insertions, 181 deletions
diff --git a/man/sd_journal_query_unique.xml b/man/sd_journal_query_unique.xml index 8f0e6b8160..ac0e5f633f 100644 --- a/man/sd_journal_query_unique.xml +++ b/man/sd_journal_query_unique.xml @@ -1,6 +1,6 @@ <?xml version='1.0'?> <!--*-nxml-*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" - "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. @@ -23,193 +23,184 @@ <refentry id="sd_journal_query_unique"> - <refentryinfo> - <title>sd_journal_query_unique</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_query_unique</refentrytitle> - <manvolnum>3</manvolnum> - </refmeta> - - <refnamediv> - <refname>sd_journal_query_unique</refname> - <refname>sd_journal_enumerate_unique</refname> - <refname>sd_journal_restart_unique</refname> - <refname>SD_JOURNAL_FOREACH_UNIQUE</refname> - <refpurpose>Read unique data fields from the journal</refpurpose> - </refnamediv> - - <refsynopsisdiv> - <funcsynopsis> - <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> - - <funcprototype> - <funcdef>int <function>sd_journal_query_unique</function></funcdef> - <paramdef>sd_journal *<parameter>j</parameter></paramdef> - <paramdef>const char *<parameter>field</parameter></paramdef> - </funcprototype> - - <funcprototype> - <funcdef>int <function>sd_journal_enumerate_unique</function></funcdef> - <paramdef>sd_journal *<parameter>j</parameter></paramdef> - <paramdef>const void **<parameter>data</parameter></paramdef> - <paramdef>size_t *<parameter>length</parameter></paramdef> - </funcprototype> - - <funcprototype> - <funcdef>void <function>sd_journal_restart_unique</function></funcdef> - <paramdef>sd_journal *<parameter>j</parameter></paramdef> - </funcprototype> - - <funcprototype> - <funcdef><function>SD_JOURNAL_FOREACH_UNIQUE</function></funcdef> - <paramdef>sd_journal *<parameter>j</parameter></paramdef> - <paramdef>const void *<parameter>data</parameter></paramdef> - <paramdef>size_t <parameter>length</parameter></paramdef> - </funcprototype> - - </funcsynopsis> - </refsynopsisdiv> - - <refsect1> - <title>Description</title> - - <para><function>sd_journal_query_unique()</function> - queries the journal for all unique values the - specified field can take. It takes two arguments: the - journal to query and the field name to look - for. Well-known field names are listed on - <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Field - names must be specified without a trailing '='. After - this function has been executed successfully the field - values may be queried using - <function>sd_journal_enumerate_unique()</function>. Invoking - this call a second time will change the field name - being queried and reset the enumeration index to the - first field value that matches.</para> - - <para><function>sd_journal_enumerate_unique()</function> - may be used to iterate through all data fields which - match the previously selected field name as set with - <function>sd_journal_query_unique()</function>. On - each invocation the next field data matching the field - name is returned. The order of the returned data - fields is not defined. It takes three arguments: the - journal context object, plus a pair of pointers to - pointer/size variables where the data object and its - size shall be stored in. The returned data is in a - read-only memory map and is only valid until the next - invocation of - <function>sd_journal_enumerate_unique()</function>. Note - that the data returned will be prefixed with the field - name and '='. Note that this call is subject to the - data field size threshold as controlled by - <function>sd_journal_set_data_threshold()</function>.</para> - - <para><function>sd_journal_restart_unique()</function> - resets the data enumeration index to the beginning of - the list. The next invocation of - <function>sd_journal_enumerate_unique()</function> - will return the first field data matching the field - name again.</para> - - <para>Note that the - <function>SD_JOURNAL_FOREACH_UNIQUE()</function> macro - may be used as a handy wrapper around - <function>sd_journal_restart_unique()</function> and - <function>sd_journal_enumerate_unique()</function>.</para> - - <para>Note that these functions currently are not - influenced by matches set with - <function>sd_journal_add_match()</function> but this - might change in a later version of this - software.</para> - </refsect1> - - <refsect1> - <title>Return Value</title> - - <para><function>sd_journal_query_unique()</function> - returns 0 on success or a negative errno-style error - code. <function>sd_journal_enumerate_unique()</function> - returns a positive integer if the next field data has - been read, 0 when no more fields are known, or a - negative errno-style error - code. <function>sd_journal_restart_unique()</function> - returns nothing.</para> - </refsect1> - - <refsect1> - <title>Notes</title> - - <para>The <function>sd_journal_query_unique()</function>, - <function>sd_journal_enumerate_unique()</function> and - <function>sd_journal_restart_unique()</function> - interfaces are available as a shared library, which can - be compiled and linked to with the - <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> - file.</para> - </refsect1> - - <refsect1> - <title>Examples</title> - - <para>Use the - <function>SD_JOURNAL_FOREACH_UNIQUE</function> macro - to iterate through all values a field of the journal - can take. The following example lists all unit names - referenced in the journal:</para> - - <programlisting>#include <stdio.h> + <refentryinfo> + <title>sd_journal_query_unique</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_query_unique</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_journal_query_unique</refname> + <refname>sd_journal_enumerate_unique</refname> + <refname>sd_journal_restart_unique</refname> + <refname>SD_JOURNAL_FOREACH_UNIQUE</refname> + <refpurpose>Read unique data fields from the journal</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> + + <funcprototype> + <funcdef>int <function>sd_journal_query_unique</function></funcdef> + <paramdef>sd_journal *<parameter>j</parameter></paramdef> + <paramdef>const char *<parameter>field</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_enumerate_unique</function></funcdef> + <paramdef>sd_journal *<parameter>j</parameter></paramdef> + <paramdef>const void **<parameter>data</parameter></paramdef> + <paramdef>size_t *<parameter>length</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>void <function>sd_journal_restart_unique</function></funcdef> + <paramdef>sd_journal *<parameter>j</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef><function>SD_JOURNAL_FOREACH_UNIQUE</function></funcdef> + <paramdef>sd_journal *<parameter>j</parameter></paramdef> + <paramdef>const void *<parameter>data</parameter></paramdef> + <paramdef>size_t <parameter>length</parameter></paramdef> + </funcprototype> + + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_journal_query_unique()</function> queries the + journal for all unique values the specified field can take. It + takes two arguments: the journal to query and the field name to + look for. Well-known field names are listed on + <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + Field names must be specified without a trailing '='. After this + function has been executed successfully the field values may be + queried using <function>sd_journal_enumerate_unique()</function>. + Invoking this call a second time will change the field name being + queried and reset the enumeration index to the first field value + that matches.</para> + + <para><function>sd_journal_enumerate_unique()</function> may be + used to iterate through all data fields which match the previously + selected field name as set with + <function>sd_journal_query_unique()</function>. On each invocation + the next field data matching the field name is returned. The order + of the returned data fields is not defined. It takes three + arguments: the journal context object, plus a pair of pointers to + pointer/size variables where the data object and its size shall be + stored in. The returned data is in a read-only memory map and is + only valid until the next invocation of + <function>sd_journal_enumerate_unique()</function>. Note that the + data returned will be prefixed with the field name and '='. Note + that this call is subject to the data field size threshold as + controlled by + <function>sd_journal_set_data_threshold()</function>.</para> + + <para><function>sd_journal_restart_unique()</function> resets the + data enumeration index to the beginning of the list. The next + invocation of <function>sd_journal_enumerate_unique()</function> + will return the first field data matching the field name + again.</para> + + <para>Note that the + <function>SD_JOURNAL_FOREACH_UNIQUE()</function> macro may be used + as a handy wrapper around + <function>sd_journal_restart_unique()</function> and + <function>sd_journal_enumerate_unique()</function>.</para> + + <para>Note that these functions currently are not influenced by + matches set with <function>sd_journal_add_match()</function> but + this might change in a later version of this software.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para><function>sd_journal_query_unique()</function> returns 0 on + success or a negative errno-style error code. + <function>sd_journal_enumerate_unique()</function> returns a + positive integer if the next field data has been read, 0 when no + more fields are known, or a negative errno-style error code. + <function>sd_journal_restart_unique()</function> returns + nothing.</para> + </refsect1> + + <refsect1> + <title>Notes</title> + + <para>The <function>sd_journal_query_unique()</function>, + <function>sd_journal_enumerate_unique()</function> and + <function>sd_journal_restart_unique()</function> interfaces are + available as a shared library, which can be compiled and linked to + with the + <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> + file.</para> + </refsect1> + + <refsect1> + <title>Examples</title> + + <para>Use the <function>SD_JOURNAL_FOREACH_UNIQUE</function> macro + to iterate through all values a field of the journal can take. The + following example lists all unit names referenced in the + journal:</para> + + <programlisting>#include <stdio.h> #include <string.h> #include <systemd/sd-journal.h> int main(int argc, char *argv[]) { - sd_journal *j; - const void *d; - size_t l; - int r; - - r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY); - if (r < 0) { - fprintf(stderr, "Failed to open journal: %s\n", strerror(-r)); - return 1; - } - r = sd_journal_query_unique(j, "_SYSTEMD_UNIT"); - if (r < 0) { - fprintf(stderr, "Failed to query journal: %s\n", strerror(-r)); - return 1; - } - SD_JOURNAL_FOREACH_UNIQUE(j, d, l) - printf("%.*s\n", (int) l, (const char*) d); - sd_journal_close(j); - return 0; + sd_journal *j; + const void *d; + size_t l; + int r; + + r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY); + if (r < 0) { + fprintf(stderr, "Failed to open journal: %s\n", strerror(-r)); + return 1; + } + r = sd_journal_query_unique(j, "_SYSTEMD_UNIT"); + if (r < 0) { + fprintf(stderr, "Failed to query journal: %s\n", strerror(-r)); + return 1; + } + SD_JOURNAL_FOREACH_UNIQUE(j, d, l) + printf("%.*s\n", (int) l, (const char*) d); + sd_journal_close(j); + return 0; }</programlisting> - </refsect1> + </refsect1> - <refsect1> - <title>See Also</title> + <refsect1> + <title>See Also</title> - <para> - <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, - <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>, - <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, - <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>, - <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>, - <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry> - </para> - </refsect1> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> </refentry> |