1REHASH(1)                           OpenSSL                          REHASH(1)
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NAME

6       openssl-c_rehash, openssl-rehash, c_rehash, rehash - Create symbolic
7       links to files named by the hash values
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SYNOPSIS

10       openssl rehash [-h] [-help] [-old] [-n] [-v] [ directory...]
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12       c_rehash flags...
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DESCRIPTION

15       On some platforms, the OpenSSL rehash command is available as an
16       external script called c_rehash.  They are functionally equivalent,
17       except for minor differences noted below.
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19       rehash scans directories and calculates a hash value of each ".pem",
20       ".crt", ".cer", or ".crl" file in the specified directory list and
21       creates symbolic links for each file, where the name of the link is the
22       hash value.  (If the platform does not support symbolic links, a copy
23       is made.)  This utility is useful as many programs that use OpenSSL
24       require directories to be set up like this in order to find
25       certificates.
26
27       If any directories are named on the command line, then those are
28       processed in turn. If not, then the SSL_CERT_DIR environment variable
29       is consulted; this should be a colon-separated list of directories,
30       like the Unix PATH variable.  If that is not set then the default
31       directory (installation-specific but often /usr/local/ssl/certs) is
32       processed.
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34       In order for a directory to be processed, the user must have write
35       permissions on that directory, otherwise an error will be generated.
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37       The links created are of the form "HHHHHHHH.D", where each H is a
38       hexadecimal character and D is a single decimal digit.  When processing
39       a directory, rehash will first remove all links that have a name in
40       that syntax, even if they are being used for some other purpose.  To
41       skip the removal step, use the -n flag.  Hashes for CRL's look similar
42       except the letter r appears after the period, like this: "HHHHHHHH.rD".
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44       Multiple objects may have the same hash; they will be indicated by
45       incrementing the D value. Duplicates are found by comparing the full
46       SHA-1 fingerprint. A warning will be displayed if a duplicate is found.
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48       A warning will also be displayed if there are files that cannot be
49       parsed as either a certificate or a CRL or if more than one such object
50       appears in the file.
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52   Script Configuration
53       The c_rehash script uses the openssl program to compute the hashes and
54       fingerprints. If not found in the user's PATH, then set the OPENSSL
55       environment variable to the full pathname.  Any program can be used, it
56       will be invoked as follows for either a certificate or CRL:
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58         $OPENSSL x509 -hash -fingerprint -noout -in FILENAME
59         $OPENSSL crl -hash -fingerprint -noout -in FILENAME
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61       where FILENAME is the filename. It must output the hash of the file on
62       the first line, and the fingerprint on the second, optionally prefixed
63       with some text and an equals sign.
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OPTIONS

66       -help -h
67           Display a brief usage message.
68
69       -old
70           Use old-style hashing (MD5, as opposed to SHA-1) for generating
71           links to be used for releases before 1.0.0.  Note that current
72           versions will not use the old style.
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74       -n  Do not remove existing links.  This is needed when keeping new and
75           old-style links in the same directory.
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77       -compat
78           Generate links for both old-style (MD5) and new-style (SHA1)
79           hashing.  This allows releases before 1.0.0 to use these links
80           along-side newer releases.
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82       -v  Print messages about old links removed and new links created.  By
83           default, rehash only lists each directory as it is processed.
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ENVIRONMENT

86       OPENSSL
87           The path to an executable to use to generate hashes and
88           fingerprints (see above).
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90       SSL_CERT_DIR
91           Colon separated list of directories to operate on.  Ignored if
92           directories are listed on the command line.
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SEE ALSO

95       openssl(1), crl(1).  x509(1).
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98       Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved.
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100       Licensed under the OpenSSL license (the "License").  You may not use
101       this file except in compliance with the License.  You can obtain a copy
102       in the file LICENSE in the source distribution or at
103       <https://www.openssl.org/source/license.html>.
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1071.1.1l                            2021-09-15                         REHASH(1)
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