1SD_ID128_TO_STRING(3)         sd_id128_to_string         SD_ID128_TO_STRING(3)
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NAME

6       sd_id128_to_string, sd_id128_from_string - Format or parse 128-bit IDs
7       as strings
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SYNOPSIS

10       #include <systemd/sd-id128.h>
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12       char *sd_id128_to_string(sd_id128_t id, char s[33]);
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14       int sd_id128_from_string(const char *s, sd_id128_t *ret);
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DESCRIPTION

17       sd_id128_to_string() formats a 128-bit ID as a character string. It
18       expects the ID and a string array capable of storing 33 characters. The
19       ID will be formatted as 32 lowercase hexadecimal digits and be
20       terminated by a NUL byte.
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22       sd_id128_from_string() implements the reverse operation: it takes a 33
23       character string with 32 hexadecimal digits (either lowercase or
24       uppercase, terminated by NUL) and parses them back into a 128-bit ID
25       returned in ret. Alternatively, this call can also parse a 37-character
26       string with a 128-bit ID formatted as RFC UUID. If ret is passed as
27       NULL the function will validate the passed ID string, but not actually
28       return it in parsed form.
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30       Note that when parsing 37 character UUIDs this is done strictly in Big
31       Endian byte order, i.e. according to RFC4122[1] Variant 1 rules, even
32       if the UUID encodes a different variant. This matches behaviour in
33       various other Linux userspace tools. It's probably wise to avoid UUIDs
34       of other variant types.
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36       For more information about the "sd_id128_t" type see sd-id128(3). Note
37       that these calls operate the same way on all architectures, i.e. the
38       results do not depend on endianness.
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40       When formatting a 128-bit ID into a string, it is often easier to use a
41       format string for printf(3). This is easily done using the
42       SD_ID128_FORMAT_STR and SD_ID128_FORMAT_VAL() macros. For more
43       information see sd-id128(3).
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RETURN VALUE

46       sd_id128_to_string() always succeeds and returns a pointer to the
47       string array passed in.  sd_id128_from_string() returns 0 on success,
48       in which case ret is filled in, or a negative errno-style error code.
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NOTES

51       These APIs are implemented as a shared library, which can be compiled
52       and linked to with the libsystemd pkg-config(1) file.
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SEE ALSO

55       systemd(1), sd-id128(3), printf(3)
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NOTES

58        1. RFC4122
59           https://tools.ietf.org/html/rfc4122
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63systemd 249                                              SD_ID128_TO_STRING(3)