Question

How can you create an md5 hash for a string on a mac using bash? md5sum does not exist in my environment. I did a man for md5 but I’m confused about what that really does.

md5 "string"

does not return a hash.

Answer 1

This should work –

[jaypal:~/Temp] echo "this will be hashed" | md5
2caf9daf910b5ef86796f74c20b7e0b

or if you prefer here string notation then –

[jaypal:~/Temp] md5 <<< 'this will be hashed'
55be2dc2df2c1cc7bad72a0ecb338841

UPDATE:

Per the man page, you can play around with any of the following options

[jaypal:~/Temp] man md5
MD5(1)           General Commands Manual           MD5(1)
...
NAME
     md5 – calculate a message-digest fingerprint (checksum) for a file
-s string
        Print a checksum of the given string.

-p      Echo stdin to stdout and append the checksum to stdout.

-q      Quiet mode - only the checksum is printed out.  Overrides the -r option.
...

[jaypal:~/Temp] md5 -s 'this will be encrypted'
MD5 ("this will be encrypted") = 502810f799de274ff7840a1549cd028a

[jaypal:~/Temp] md5 -qs 'this will be encrypted'
502810f799de274ff7840a1549cd028a

Note: MD5 always produces the same hash. The reason you find the output different from the example given above is due to a point that has been made in the comments. The first two examples use the trailing newline character to produce the hash. To avoid that, you can use:

[jaypal:~/Temp] echo -n "this will be encrypted" | md5
502810f799de274ff7840a1549cd028a

For example, if you use echo -n "string" | md5 (note the -n option), you get b45cffe084dd3d20d928bee85e7b0f21. But, if you use echo "string" | md5, you get b80fa55b1234f1935cea559d9efbc39a.

Or, verify it with the shell:

➜  [jaypal:~/Temp] [ $(echo "HOLA" | md5) = $(echo "HOLA" -n | md5) ]; echo "$?"
1
# 1 -> False. Hence, the result from echoing "HOLA" toggling the -n flag
# outputs different md5 checksums.