Why doesn't md5 match Perl's Digest::MD5 output?

Running the md5 function from the ksh terminal does not matching the output from a simple Perl script.

In the terminal I run:

echo -n abc | md5
62fecf21103616开发者_开发技巧856d72e6ffc9bcb06b

If I run it using Perl:

use Digest::MD5 qw(md5_hex);

foreach (@ARGV) {
   print "Digest is ", md5_hex($_), "\n";
}
exit

I get

./perl_test.sh abc
Digest is 900150983cd24fb0d6963f7d28e17f72

In all the samples I see and the sample of the md5 function itself the Perl one looks right but the one using just Ksh doesn't:

md5 -x
MD5 test suite:
MD5 ("") = d41d8cd98f00b204e9800998ecf8427e
MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661
MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72

use the more portable printf

printf "abc" | md5

Your echo doesn't recognize the -n option, so you are hashing the string '-n abc\n'.

Further to GregS's answer, some examples:

$ md5 -s "-n abc"$'\012' # \012 = newline
MD5 ("-n abc
") = 62fecf21103616856d72e6ffc9bcb06b

And

$ md5 -s "abc"
MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72

When I run into these issues, I normally do something like this to check what my output is (for example showing tabs, versus spaces and so forth)

$ echo abc | hexdump -c
0000000   a   b   c  \n                                                
0000004