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75 lines
3.6 KiB
Groff
75 lines
3.6 KiB
Groff
'\" t
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.TH "SD_JOURNAL_GET_CURSOR" "3" "" "systemd 219" "sd_journal_get_cursor"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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sd_journal_get_cursor, sd_journal_test_cursor \- Get cursor string for or test cursor string against the current journal entry
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.SH "SYNOPSIS"
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.sp
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.ft B
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.nf
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#include <systemd/sd\-journal\&.h>
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.fi
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.ft
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.HP \w'int\ sd_journal_get_cursor('u
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.BI "int sd_journal_get_cursor(sd_journal\ *" "j" ", char\ **" "cursor" ");"
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.HP \w'int\ sd_journal_test_cursor('u
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.BI "int sd_journal_test_cursor(sd_journal\ *" "j" ", const\ char\ *" "cursor" ");"
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.SH "DESCRIPTION"
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.PP
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\fBsd_journal_get_cursor()\fR
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returns a cursor string for the current journal entry\&. A cursor is a serialization of the current journal position formatted as text\&. The string only contains printable characters and can be passed around in text form\&. The cursor identifies a journal entry globally and in a stable way and may be used to later seek to it via
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\fBsd_journal_seek_cursor\fR(3)\&. The cursor string should be considered opaque and not be parsed by clients\&. Seeking to a cursor position without the specific entry being available locally will seek to the next closest (in terms of time) available entry\&. The call takes two arguments: a journal context object and a pointer to a string pointer where the cursor string will be placed\&. The string is allocated via libc
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\fBmalloc\fR(3)
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and should be freed after use with
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\fBfree\fR(3)\&.
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.PP
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Note that
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\fBsd_journal_get_cursor()\fR
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will not work before
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\fBsd_journal_next\fR(3)
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(or related call) has been called at least once, in order to position the read pointer at a valid entry\&.
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.PP
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\fBsd_journal_test_cursor()\fR
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may be used to check whether the current position in the journal matches the specified cursor\&. This is useful since cursor strings do not uniquely identify an entry: the same entry might be referred to by multiple different cursor strings, and hence string comparing cursors is not possible\&. Use this call to verify after an invocation of
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\fBsd_journal_seek_cursor\fR(3)
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whether the entry being sought to was actually found in the journal or the next closest entry was used instead\&.
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.SH "RETURN VALUE"
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.PP
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\fBsd_journal_get_cursor()\fR
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returns 0 on success or a negative errno\-style error code\&.
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\fBsd_journal_test_cursor()\fR
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returns positive if the current entry matches the specified cursor, 0 if it does not match the specified cursor or a negative errno\-style error code on failure\&.
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.SH "NOTES"
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.PP
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The
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\fBsd_journal_get_cursor()\fR
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and
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\fBsd_journal_test_cursor()\fR
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interfaces are available as a shared library, which can be compiled and linked to with the
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\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
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file\&.
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.SH "SEE ALSO"
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.PP
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\fBsystemd\fR(1),
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\fBsd-journal\fR(3),
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\fBsd_journal_open\fR(3),
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\fBsd_journal_seek_cursor\fR(3)
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