set -e and short tests

Question

When I was new to shell scripting, I used a lot of short tests instead of if statements, like false && true.

Then later I learned using set -e, and found my scripts were dying for some reason, and they would work if I replaced the short tests with full if statements. Now, the time has gone, and I still use full if statements only.

The most interesting is that if I open an interactive shell and do the following:

set -e
false && true
echo $?

it returns 1 but the shell doesn't die!

I see that I have been wasting too many lines of code. Anyone could explain to me how can I use set -e with short tests safely, eg. without the script dying?

Answer 1

Regarding my problem of the script unexpectedly dying, it is due to running those short tests in a subshell, or from a function, and said function returns a value different than zero:

Original example:

$ set -e
$ false && true
$ echo $?
1

Using a subshell or function:

$ set -e
$ (false && true)
<script died>

$ set -e
$ variable=$(false && true)
<script died>

$ set -e
$ foo()(false && true)
$ foo
<script died>

$ set -e
$ foo(){ false && true; }
$ foo
<script died>

Possible solutions:

$ set -e
$ (false && true ||:)
$ (false && true) ||:
$ (if false; then true; fi)