man: document that sd_journal_print() strips trailing whitespace

1 files changed, 35 insertions, 51 deletions

diff --git a/man/sd_journal_print.xml b/man/sd_journal_print.xml
index 17fdc9c1f2..6fe078d88e 100644
--- a/man/sd_journal_print.xml
+++ b/man/sd_journal_print.xml
@@ -93,27 +93,20 @@
   <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
+    <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>.
-    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.</para>
+    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). Leading whitespace (as well as inner whitespace) is left unmodified however.</para>
 
     <para><function>sd_journal_printv()</function> is similar to
     <function>sd_journal_print()</function> but takes a variable
@@ -123,35 +116,26 @@
     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.</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.</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 wil 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>
@@ -174,8 +158,8 @@
     <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>
+                "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