md5sum 生成 经md5加密后的字符串

➜  ~ echo -n 'admin' | md5sum
21232f297a57a5a743894a0e4a801fc3  -
➜  ~ md5sum -h
md5sum: invalid option -- 'h'
Try `md5sum --help' for more information.
➜  ~ md5sum --help
Usage: md5sum [OPTION]... [FILE]...
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
-t, --text              read in text mode (default)
Note: There is no difference between binary and text mode option on GNU system.

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

--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 type (`*' for binary, ` ' for
text), and name for each FILE.

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/>
For complete documentation, run: info coreutils 'md5sum invocation'