how much are "historic" issues with test / [ still an issue

[Christoph Anton Mitterer]

Hey again.

Via the other thread I've recently stumbled over test/[’s -o and -a
options being deprecated for some reasons, as e.g. described in the
"Rationale" section of:
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html


I wondered how much shells (especially bash, but perhaps also dash if
someone coincidentally knows) are still affected by this?



1) > test "$1" -a "$2"
   > should be written as:
   > test "$1" && test "$2"

So AFAIU, the problem here is that whenever any user input ($var)
contains a string that might be taken as a operator (i.e. ( ! or
starting with -) ambiguous results could come out.

The example given was $1 set to ! and $2 being empty, in which case, I
guess -a is taken as a string as if ! $var was written.

But the result seems to be the same as with && ... and even if one
takes bash with has the unary -a FILE ... it doesn't seem to do a:
! ( -a FILE )



2) Allegedly on "historical systems" (only?)
   > The two commands:
   > test "$1"
   > test ! "$1"
   should be written as:
   > test -n "$1"
   > test -z "$1"

Even more importantly for me, cases like:
   > test "$response" = "expected string"
   shall be written as:
   > test "X$response" = "Xexpected string"

I guess the leading X is simply to "escape" any possible meta-character
like ( ! or -, right ?

If one doesn't use more than 3 params, i.e. no parentheses -a -o, is
there any chance that a:
"$str1" op "str2"
could be still taken wrongly, if not adding the X?


So are these still an issue with modern versions of bash (and dash,
etc.)?


At least the case of:
   > test -d $1 -o -d $2
seems to be "still" an issue if $1 is =


Thanks,
Chris.