(Cc: Chet Ramey... forgot to send it to list...oop)
Chet Ramey wrote:
On 10/10/15 11:01 PM, Linda Walsh wrote:
a= read a <<< x;echo $?
0
declare -p a
declare -- a="x"
# the manpage claims "one line is read from [the input], and the result
# is split by words and assigns 1st word to 1st var and so forth, but
# apparently the reading of 1 line is optional -- though this is
consistent
# with the fact that read can be told to read some number of characters
and # return when the limit is reached. So technically, read doesn't
"read one line",
# but read whatever is on 'input' up to 1 line. (DOC clarification?)
This is terribly wrong.
The command in question is `a= read a <<< x'.
The here-string construct takes the following word and, like a here
document, makes it the standard input to the command. The standard
input is then a file consisting of a single line: x\n.
It's basically shorthand for
read a <<EOF
x
EOF
So, `read' reads the single line from its standard input and assigns it
to the variable `a'.
----
I wasn't sure if it put the "\n" at the end in a 1-line example.
Does it also use a tmp file and use process-substitution, or is
that only when parens are present? I.e.
read a < <( echo x)
I'm under the impression, uses a tmp file.
does the read a <<< x
also use a tmp file?
I.e. is
readarray -t a < <( echo -e 'x\ny\n')
declare -p a
declare -a a='([0]="x" [1]="y")'
implemented the same way as
a=(x y)
b=$(printf "%s\n" ${a[@]})
readarray -t ar <<< "${b[@]}"
declare -p a
declare -a a='([0]="x" [1]="y")'