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2021-07-27 - here documents & here strings

this is a bash post. i knew about here documents in bash, but i didn't know what it is called. a here document is something like this:

cat << eof
hello world
eof

it tells bash to redirect the current input to stdin, until you reach the token defined right after the <<. but the other day i wanted to replace stdin with the content of an environment variable. the approach i came up with was:

avar="hello world"
echo "$avar" | cat

but there is another, arguably better, way to do that with a here string:

avar="hello world"
cat <<< $avar

i never noticed the <<< here string syntax before, so i thought i'd share. you can find some more information on here strings and here documents here:

=> http://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#Here-Documents