Using two here strings

bash shell heredoc

You can't use two herestrings as input to the same command. In effect, the latest one will replace all others. Demonstration:

cat <<< "string 1" <<< "string 2" <<< "string 3"# only shows "string 3"

On the other hand, if what you want is really diff two immediate inputs, you can do it this way:

diff <(echo "string 1") <(echo "string 2")

bash shell heredoc

You can simply concatenate the two strings:

cat <<< "string1""string2"

(not the lack of space between the two). The here string now consists of a single word whose contents are the contents of the two strings.

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