Chris F.A. Johnson wrote:
On Fri, 9 Jun 2017, L A Walsh wrote:
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First problem: If you are assigning a string to a variable,
you need to put quotes around the string.
You don't need to quote it unless it contains literal whitespace.
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Not true if you want to reproduce the string as output by
"declare". Since declare doesn't output the literal value in a
variable, but an expanded one, you need to put quotes around any
var that you intend to expand with 'declare'.
Greg's example:
imadev:~$ x=$'foo\nbar'
imadev:~$ declare -p x
declare -- x="foo
bar"
Shows that "declare" isn't quoting its output such that it can be
used for assignment to a var, or as 'read' input.
To do that, you can use "printf %q" -- as in:
x=$'foo\nbar'
printf -v qx "%q" "$x"
printf "%s\n" "$qx"
$'foo\nbar'
I used double quotes around the original:
x="$'foo\nbar'"
Which gives:
printf "%s\n" "$x"
$'foo\nbar'
The exact same output.
I.e. you need to double quote Greg's input for it to be re-usable as input.
