linux下校验文件的md5值

文件的md5值是确认这个文件是否完整的一个重要依据。

linux下有一个软件叫做md5sum，他可以用来校验文件的MD5值。

      md5sum - compute and check MD5 message digest


用法很简单，md5sum [文件名]
然后就会计算出文件的MD5值了。


MD5SUM(1)                        User Commands                       MD5SUM(1)

NAME
       md5sum - compute and check MD5 message digest

SYNOPSIS
       md5sum [OPTION]... [FILE]...

DESCRIPTION
       Print  or check MD5 (128-bit) checksums.  With no FILE, or when FILE is
       -, read standard input.

       -b, --binary
              read in binary mode

       -c, --check
              read MD5 sums from the FILEs and check them

       --tag  create a BSD-style checksum

       -t, --text
              read in text mode (default)

   The following three options are useful only when verifying checksums:
       --quiet
              don't print OK for each successfully verified file

       --status
              don't output anything, status code shows success

       -w, --warn
              warn about improperly formatted checksum lines

       --strict
              with --check, exit non-zero for any invalid input

       --help display this help and exit

       --version
              output version information and exit
       The sums are computed as described in RFC  1321.   When  checking,  the
       input  should  be a former output of this program.  The default mode is
       to print a line with checksum, a character indicating input  mode  ('*'
       for binary, space for text), and name for each FILE.

BUGS
       The MD5 algorithm should not be used any more for security related pur‐
       poses.  Instead, better use an SHA-2 algorithm, implemented in the pro‐
       grams sha224sum(1), sha256sum(1), sha384sum(1), sha512sum(1)

AUTHOR
       Written by Ulrich Drepper, Scott Miller, and David Madore.

REPORTING BUGS
       Report md5sum bugs to bug-coreutils@gnu.org
       GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
       General help using GNU software: <http://www.gnu.org/gethelp/>
       Report md5sum translation bugs to <http://translationproject.org/team/>

COPYRIGHT
       Copyright  ©  2013  Free Software Foundation, Inc.  License GPLv3+: GNU
       GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free  to  change  and  redistribute  it.
       There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       The  full  documentation  for md5sum is maintained as a Texinfo manual.
       If the info and md5sum programs are properly installed  at  your  site,
       the command

              info coreutils 'md5sum invocation'

       should give you access to the complete manual.