xenial (1) c_rehash.1ssl.gz

Provided by: openssl_1.0.2g-1ubuntu4.20_amd64 bug

NAME

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

SYNOPSIS

       c_rehash [-old] [-h] [-n] [-v] [ directory...]

DESCRIPTION

       c_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
       certificates.

       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 shold 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 processed.

       In order for a directory to be processed, the user must have write permissions on that directory,
       otherwise it will be skipped.  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, c_rehash will first
       remove all links that have a name in that syntax. If you have links in that format used for other
       purposes, they will be removed.  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.

       The program 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.

OPTIONS

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

       -h  Display a brief usage message.

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

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

ENVIRONMENT

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

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

SEE ALSO

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