Re: read and env variables + POSIX => SEGFAULT

[Chet Ramey]

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'.
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/