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REHASH(1)			    OpenSSL			     REHASH(1)

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

       openssl rehash [-h] [-help] [-old] [-n] [-v] [ directory...]

       c_rehash	flags...

       On some platforms, the OpenSSL rehash command is	available as an
       external	script called c_rehash.	 They are functionally equivalent,
       except for minor	differences noted below.

       rehash scans directories	and calculates a hash value of each ".pem",
       ".crt", ".cer", or ".crl" file in the specified directory list and
       creates symbolic	links for each file, where the name of the link	is the
       hash value.  (If	the platform does not support symbolic links, a	copy
       is made.)  This utility is useful as many programs that use OpenSSL
       require directories to be set up	like this in order to find

       If any directories are named on the command line, then those are
       processed in turn. If not, then the SSL_CERT_DIR	environment variable
       is consulted; this should be a colon-separated list of directories,
       like the	Unix PATH variable.  If	that is	not set	then the default
       directory (installation-specific	but often /usr/local/ssl/certs)	is

       In order	for a directory	to be processed, the user must have write
       permissions on that directory, otherwise	an error will be generated.

       The links created are of	the form "HHHHHHHH.D", where each H is a
       hexadecimal character and D is a	single decimal digit.  When processing
       a directory, rehash will	first remove all links that have a name	in
       that syntax, even if they are being used	for some other purpose.	 To
       skip the	removal	step, use the -n flag.	Hashes for CRL's look similar
       except the letter r appears after the period, like this:	"HHHHHHHH.rD".

       Multiple	objects	may have the same hash;	they will be indicated by
       incrementing the	D value. Duplicates are	found by comparing the full
       SHA-1 fingerprint. A warning will be displayed if a duplicate is	found.

       A warning will also be displayed	if there are files that	cannot be
       parsed as either	a certificate or a CRL or if more than one such	object
       appears in the file.

   Script Configuration
       The c_rehash script uses	the openssl program to compute the hashes and
       fingerprints. If	not found in the user's	PATH, then set the OPENSSL
       environment variable to the full	pathname.  Any program can be used, it
       will be invoked as follows for either a certificate or CRL:

	 $OPENSSL x509 -hash -fingerprint -noout -in FILENAME
	 $OPENSSL crl -hash -fingerprint -noout	-in FILENAME

       where FILENAME is the filename. It must output the hash of the file on
       the first line, and the fingerprint on the second, optionally prefixed
       with some text and an equals sign.

       -help -h
	   Display a brief usage message.

	   Use old-style hashing (MD5, as opposed to SHA-1) for	generating
	   links to be used for	releases before	1.0.0.	Note that current
	   versions will not use the old style.

       -n  Do not remove existing links.  This is needed when keeping new and
	   old-style links in the same directory.

	   Generate links for both old-style (MD5) and new-style (SHA1)
	   hashing.  This allows releases before 1.0.0 to use these links
	   along-side newer releases.

       -v  Print messages about	old links removed and new links	created.  By
	   default, rehash only	lists each directory as	it is processed.

	   The path to an executable to	use to generate	hashes and
	   fingerprints	(see above).

	   Colon separated list	of directories to operate on.  Ignored if
	   directories are listed on the command line.

       openssl(1), crl(1).  x509(1).

       Copyright 2015-2018 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (the "License").  You	may not	use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at

1.1.1l				  2021-08-24			     REHASH(1)


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