What does "<<<" mean on a bash command line? And where is it documented?

Question

What does <<< mean in this command line?

bc <<< "1 + 1"

It doesn't seem to a combination of < and <<, and I can't find documentation for it. It seems to behave just like

echo "1 + 1" | bc

Also works in ksh, but not in sh.

@anubhava You don't even need to know what they are called; it's sufficient to search for `<< — rici, Sep 11 '14 at 22:19

score 5 · Accepted Answer · answered Sep 11 '14 at 21:33

5

It introduces a here string, documented near the end of the section on input and output redirections. A here string is just a one-word here document:

bc <<< "1 + 1"

is equivalent to

bc <<EOF
1 + 1
EOF

answered Sep 11 '14 at 21:33

chepner

score 2 · Answer 2 · answered Sep 11 '14 at 21:32

2

That is the here string operator. See here string operator document.

answered Sep 11 '14 at 21:32

Peter Pei Guo

score 0 · Answer 3 · answered Sep 11 '14 at 21:38

0

man ksh

You can perform a search in a manual by typing / (slash) follow by what you search, like with less program.

answered Sep 11 '14 at 21:38

mcoolive

3 Answers3