What is the meaning of <<<

Question

I found this code in a script at the end of a while loop

done <<< $filenames

In the script, $filenames is a variable used to collect a list of files from a database. The loop processes each sub-string in the $filenames list. The question I have is what does the <<< do?

Yes I read the man page and searched. Perhaps my search was too specific. — cbcalvin, Jun 19 '14 at 18:06
http://www.gnu.org/software/bash/manual/bashref.html#Here-Strings — Barmar, Jun 19 '14 at 18:08
All you have to do is open that documentation and search with the browser for `<<<` — Barmar, Jun 19 '14 at 18:08

score 1 · Answer 1 · answered Jun 19 '14 at 17:32

1

<<< is essentially a one-line heredoc (a "here string").

$ cat <<< blah
blah

which is equivalent to a heredoc like:

$ cat <<EOF
> blah
> EOF
blah

answered Jun 19 '14 at 17:32

FatalError

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Or equiv to `echo blah | cat` – Barmar Jun 19 '14 at 17:37
And the one-line heredoc provides then input to subsequent READ loop. – cbcalvin Jun 19 '14 at 18:07
@Barmar Similar, but not entirely equivalent. A pipe runs each side in a sub-process, meaning variable changes would be lost. `<<<` works within the current shell process. – John Kugelman Jun 19 '14 at 18:46

score 0 · Answer 2 · answered Jun 19 '14 at 17:32

0

<<< operator is used to fed input to the corresponding command on it's left side.

answered Jun 19 '14 at 17:32

Avinash Raj

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What is the meaning of <<<

2 Answers2