Shell Programming and Scripting

$ md5sum file1
27a3024f4381f60aa6a232c2de903645  file1

$ md5sum file1 > log
$ md5sum -c log
file1: OK
$ echo $?
0

$ date >> file1
$ md5sum -c log
file1: FAILED
md5sum: WARNING: 1 computed checksum did NOT match
$ echo $?
1

$md5sum outputfile
ksh: md5sum:  not found

DGST(1)                             OpenSSL                            DGST(1)



NAME
       dgst, md5, md4, md2, sha1, sha, mdc2, ripemd160 - message digests

SYNOPSIS
       openssl dgst [-md5|-md4|-md2|-sha1|-sha|-mdc2|-ripemd160|-dss1] [-c]
       [-d] [-hex] [-binary] [-out filename] [-sign filename] [-passin arg]
       [-verify filename] [-prverify filename] [-signature filename] [-hmac
       key] [file...]

       [md5|md4|md2|sha1|sha|mdc2|ripemd160] [-c] [-d] [file...]

DESCRIPTION
       The digest functions output the message digest of a supplied file or
       files in hexadecimal form. They can also be used for digital signing
       and verification.

OPTIONS
       -c  print out the digest in two digit groups separated by colons, only
           relevant if hex format output is used.

       -d  print out BIO debugging information.

       -hex
           digest is to be output as a hex dump. This is the default case for
           a "normal" digest as opposed to a digital signature.

       -binary
           output the digest or signature in binary form.

       -out filename
           filename to output to, or standard output by default.

       -sign filename
           digitally sign the digest using the private key in "filename".

       -passin arg
           the private key password source. For more information about the
           format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).

       -verify filename
           verify the signature using the the public key in "filename".  The
           output is either "Verification OK" or "Verification Failure".

       -prverify filename
           verify the signature using the  the private key in "filename".

       -signature filename
           the actual signature to verify.

       -hmac key
           create a hashed MAC using "key".

       -rand file(s)
           a file or files containing random data used to seed the random
           number generator, or an EGD socket (see RAND_egd(3)).  Multiple
           files can be specified separated by a OS-dependent character.  The
           separator is ; for MS-Windows, , for OpenVMS, and : for all others.

       file...
           file or files to digest. If no files are specified then standard
           input is used.

NOTES
       The digest of choice for all new applications is SHA1. Other digests
       are however still widely used.

       If you wish to sign or verify data using the DSA algorithm then the
       dss1 digest must be used.

       A source of random numbers is required for certain signing algorithms,
       in particular DSA.

       The signing and verify options should only be used if a single file is
       being signed or verified.



0.9.8r                            2008-05-19                           DGST(1)