On Thu 2021-06-17 10:55:27 -0400, J C Nash wrote:
> While I've found a workaround, I was a bit surprised that a test for existence of
> a directory in a bash script did not work.
This is POSIX shell in general.
> I tried
>
> DIR="~/Something/"
Just DIR="$HOME/Something" unless you need to refer to someone else's
home.
> if [ -d "$DIR" ]; then
Heck, I'd just if [ -d ~/Something ]; then
> and got that the directory did NOT exist when it was clearly there.
>
> Workaround was to use
>
> DIR="/home/$(basename ~)/Something/"
>
> I did a bit of a search, but found no mention of the fact that ~ is not
> expanded in the if [ ] construct. Is it, in fact, "well-known" except
> to me?
It's because the tilde is in quotes.
See 2018 POSIX shell command language ยง 2.6.1 Tilde Expansion
A "tilde-prefix" consists of an unquoted <tilde> character at the
beginning of a word, followed by all of the characters preceding the
first unquoted <slash> in the word, or all the characters in the
word if there is no <slash>.
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_01
Your tilde in your command substitution is unquoted, which is why it
works.
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