diff options
Diffstat (limited to 'man/sd_journal_print.xml')
| -rw-r--r-- | man/sd_journal_print.xml | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/man/sd_journal_print.xml b/man/sd_journal_print.xml new file mode 100644 index 0000000..68a4a0a --- /dev/null +++ b/man/sd_journal_print.xml @@ -0,0 +1,272 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="sd_journal_print" xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sd_journal_print</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_journal_print</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_journal_print</refname> + <refname>sd_journal_printv</refname> + <refname>sd_journal_send</refname> + <refname>sd_journal_sendv</refname> + <refname>sd_journal_perror</refname> + <refname>SD_JOURNAL_SUPPRESS_LOCATION</refname> + <refname>sd_journal_print_with_location</refname> + <refname>sd_journal_printv_with_location</refname> + <refname>sd_journal_send_with_location</refname> + <refname>sd_journal_sendv_with_location</refname> + <refname>sd_journal_perror_with_location</refname> + + <refpurpose>Submit log entries to the journal</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> + + <funcprototype> + <funcdef>int <function>sd_journal_print</function></funcdef> + <paramdef>int <parameter>priority</parameter></paramdef> + <paramdef>const char *<parameter>format</parameter></paramdef> + <paramdef>…</paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_printv</function></funcdef> + <paramdef>int <parameter>priority</parameter></paramdef> + <paramdef>const char *<parameter>format</parameter></paramdef> + <paramdef>va_list <parameter>ap</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_send</function></funcdef> + <paramdef>const char *<parameter>format</parameter></paramdef> + <paramdef>…</paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_sendv</function></funcdef> + <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> + <paramdef>int <parameter>n</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_perror</function></funcdef> + <paramdef>const char *<parameter>message</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_print_with_location</function></funcdef> + <paramdef>const char *<parameter>file</parameter></paramdef> + <paramdef>const char *<parameter>line</parameter></paramdef> + <paramdef>const char *<parameter>func</parameter></paramdef> + <paramdef>int <parameter>priority</parameter></paramdef> + <paramdef>const char *<parameter>format</parameter></paramdef> + <paramdef>…</paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_printv_with_location</function></funcdef> + <paramdef>int <parameter>priority</parameter></paramdef> + <paramdef>const char *<parameter>file</parameter></paramdef> + <paramdef>const char *<parameter>line</parameter></paramdef> + <paramdef>const char *<parameter>func</parameter></paramdef> + <paramdef>const char *<parameter>format</parameter></paramdef> + <paramdef>va_list <parameter>ap</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_send_with_location</function></funcdef> + <paramdef>const char *<parameter>file</parameter></paramdef> + <paramdef>const char *<parameter>line</parameter></paramdef> + <paramdef>const char *<parameter>func</parameter></paramdef> + <paramdef>const char *<parameter>format</parameter></paramdef> + <paramdef>…</paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_sendv_with_location</function></funcdef> + <paramdef>const char *<parameter>file</parameter></paramdef> + <paramdef>const char *<parameter>line</parameter></paramdef> + <paramdef>const char *<parameter>func</parameter></paramdef> + <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> + <paramdef>int <parameter>n</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_perror_with_location</function></funcdef> + <paramdef>const char *<parameter>file</parameter></paramdef> + <paramdef>const char *<parameter>line</parameter></paramdef> + <paramdef>const char *<parameter>func</parameter></paramdef> + <paramdef>const char *<parameter>message</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_journal_print()</function> may be used to submit simple, plain text log entries to the system + journal. The first argument is a priority value. This is followed by a format string and its parameters, similar to + <citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> or + <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + Note that currently the resulting message will be truncated to <constant>LINE_MAX - 8</constant>. + The priority value is one of <constant>LOG_EMERG</constant>, <constant>LOG_ALERT</constant>, + <constant>LOG_CRIT</constant>, <constant>LOG_ERR</constant>, <constant>LOG_WARNING</constant>, + <constant>LOG_NOTICE</constant>, <constant>LOG_INFO</constant>, <constant>LOG_DEBUG</constant>, as defined in + <filename>syslog.h</filename>, see <citerefentry + project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> for details. It is + recommended to use this call to submit log messages in the application locale or system locale and in UTF-8 format, + but no such restrictions are enforced. Note that log messages written using this function are generally not + expected to end in a new-line character. However, as all trailing whitespace (including spaces, new-lines, + tabulators and carriage returns) are automatically stripped from the logged string, it is acceptable to specify one + (or more). Empty lines (after trailing whitespace removal) are suppressed. On non-empty lines, leading whitespace + (as well as inner whitespace) is left unmodified. </para> + + <para><function>sd_journal_printv()</function> is similar to + <function>sd_journal_print()</function> but takes a variable + argument list encapsulated in an object of type + <varname>va_list</varname> (see + <citerefentry project='man-pages'><refentrytitle>stdarg</refentrytitle><manvolnum>3</manvolnum></citerefentry> + for more information) instead of the format string. It is + otherwise equivalent in behavior.</para> + + <para><function>sd_journal_send()</function> may be used to submit structured log entries to the system journal. It + takes a series of format strings, each immediately followed by their associated parameters, terminated by + <constant>NULL</constant>. The strings passed should be of the format <literal>VARIABLE=value</literal>. The + variable name must be in uppercase and consist only of characters, numbers and underscores, and may not begin with + an underscore. (All assignments that do not follow this syntax will be ignored.) The value can be of any size and + format. It is highly recommended to submit text strings formatted in the UTF-8 character encoding only, and submit + binary fields only when formatting in UTF-8 strings is not sensible. A number of well-known fields are defined, see + <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> for + details, but additional application defined fields may be used. A variable may be assigned more than one value per + entry. If this function is used, trailing whitespace is automatically removed from each formatted field.</para> + + <para><function>sd_journal_sendv()</function> is similar to <function>sd_journal_send()</function> but takes an + array of <varname>struct iovec</varname> (as defined in <filename>uio.h</filename>, see <citerefentry + project='man-pages'><refentrytitle>readv</refentrytitle><manvolnum>3</manvolnum></citerefentry> for details) + instead of the format string. Each structure should reference one field of the entry to submit. The second argument + specifies the number of structures in the array. <function>sd_journal_sendv()</function> is particularly useful to + submit binary objects to the journal where that is necessary. Note that this function will not strip trailing + whitespace of the passed fields, but passes the specified data along unmodified. This is different from both + <function>sd_journal_print()</function> and <function>sd_journal_send()</function> described above, which are based + on format strings, and do strip trailing whitespace.</para> + + <para><function>sd_journal_perror()</function> is a similar to + <citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry> + and writes a message to the journal that consists of the passed + string, suffixed with ": " and a human-readable representation of + the current error code stored in + <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + If the message string is passed as <constant>NULL</constant> or + empty string, only the error string representation will be + written, prefixed with nothing. An additional journal field ERRNO= + is included in the entry containing the numeric error code + formatted as decimal string. The log priority used is + <constant>LOG_ERR</constant> (3).</para> + + <para>Note that <function>sd_journal_send()</function> is a + wrapper around <function>sd_journal_sendv()</function> to make it + easier to use when only text strings shall be submitted. Also, the + following two calls are mostly equivalent:</para> + + <programlisting>sd_journal_print(LOG_INFO, "Hello World, this is PID %lu!", (unsigned long) getpid()); + +sd_journal_send("MESSAGE=Hello World, this is PID %lu!", (unsigned long) getpid(), + "PRIORITY=%i", LOG_INFO, + NULL);</programlisting> + + <para>Note that these calls implicitly add fields for the source file, function name and code line where + invoked. This is implemented with macros. If this is not desired, it can be turned off by defining + <constant>SD_JOURNAL_SUPPRESS_LOCATION</constant> before including <filename>sd-journal.h</filename>. + </para> + + <para><function>sd_journal_print_with_location()</function>, + <function>sd_journal_printv_with_location()</function>, <function>sd_journal_send_with_location()</function>, + <function>sd_journal_sendv_with_location()</function>, and + <function>sd_journal_perror_with_location()</function> are similar to their counterparts without + <literal>_with_location</literal>, but accept additional parameters to explicitly set the source file + name, function, and line. Those arguments must contain valid journal entries including the variable name, + e.g. <literal>CODE_FILE=src/foo.c</literal>, <literal>CODE_LINE=666</literal>, + <literal>CODE_FUNC=myfunc</literal>. These variants are primarily useful when writing custom wrappers, + for example in bindings for a different language.</para> + + <para><citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> + and <function>sd_journal_print()</function> may + largely be used interchangeably + functionality-wise. However, note that log messages + logged via the former take a different path to the + journal server than the later, and hence global + chronological ordering between the two streams cannot + be guaranteed. Using + <function>sd_journal_print()</function> has the + benefit of logging source code line, filenames, and + functions as metadata along all entries, and + guaranteeing chronological ordering with structured + log entries that are generated via + <function>sd_journal_send()</function>. Using + <function>syslog()</function> has the benefit of being + more portable.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>The ten functions return 0 on success or a negative errno-style error code. The + <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry> + variable itself is not altered.</para> + + <para>If + <citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry> + is not running (the socket is not present), those functions do + nothing, and also return 0.</para> + </refsect1> + + <refsect1> + <title>Thread safety</title> + + <xi:include href="threads-aware.xml" xpointer="safe"/> + + <para><function>sd_journal_sendv()</function> and <function>sd_journal_sendv_with_location()</function> + are "async signal safe" in the meaning of + <citerefentry project='man-pages'><refentrytitle>signal-safety</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + </para> + + <para><function>sd_journal_print()</function>, + <function>sd_journal_printv()</function>, + <function>sd_journal_send()</function>, + <function>sd_journal_perror()</function>, + and their counterparts with <literal>_with_location</literal> + are not async signal safe.</para> + </refsect1> + + <xi:include href="libsystemd-pkgconfig.xml" /> + + <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_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='die-net'><refentrytitle>perror</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |