How to pipe md5 hash result in shell

Question

I am looking for a simple way to pipe the result of md5sum into another command. Something like this:

$echo -n 'test' | md5sum | ...

My problem is that md5sum outputs not only the hash of the string, but also an hypen, which indicates that the input came from stdin. I checked the man file and I didn't find any flags to control output.

Answer 1

You can use the command cut; it allows you to cut a certain character/byte range from every input line. Since the MD5 hash has fixed length (32 characters), you can use the option -c 1-32 to keep only the first 32 characters from the input line:

echo -n test | md5sum | cut -c 1-32

Alternatively, you can tell cut to split the line at the every space and output only the first field: (note the quotes around the space character)

echo -n test | md5sum | cut -d " " -f 1

See the cut manpage for more options.

Answer 2

You can cut it:

echo -n 'test' | md5sum | cut -d' ' -f1

Here, -d' ' chooses space as delimiter, and -f1 asks for the first field (before a delimiter).

Answer 3

Using awk works fine too :

echo -n 'test' | md5sum | awk '{print $1}'

Another way is making a substring. Because you know md5 hash is a string with 32 characters, you could use :

HASH=$(echo -n 'test' | md5sum -) && echo ${HASH:0:32}

It's just string manipulations, so you got the choice !