Re: typeset -p on an empty integer variable is an error. (plus -v test w/ array elements)

[John Kearney]

Am 14.01.2013 14:33, schrieb Greg Wooledge:
> On Sun, Jan 13, 2013 at 03:31:24AM +0100, John Kearney wrote:
>> set -o errexit
>> test_func() {
>>     [ ! -d test ] && echo test2
>> }
>>
>> echo test3
>> test_func
>> echo test4
>>
>> now so long as test doesn't exist in the cwd it should errexit.
>> at least it did for me just now.
> Cannot reproduce.
>
> imadev:~$ cat bar
> #!/bin/bash
>
> set -e
> f() { test ! -d nosuchdir && echo no dir; }
> f
> echo survived
> imadev:~$ ./bar
> no dir
> survived



the "no dir" above means that the test didn't fail. The exit only
happens if the test fails. Sorry I keep seeming to make typos. I really
need more sleep.
this should exit.
#!/bin/bash

set -e
f() { test -d nosuchdir && echo no dir; }
echo testings
f
echo survived




All I was pointing out that its safer to use syntax

[] ||

or

[] && ||

you always need a || on a one liner to make sure the return value of the
line is a 0.
this isn't necessary in the script body I think but in a function it is,
unless its the last command then it will be auto returned..

but lets say you want to do 2 things in a function you have to do
something like.
f(){
    mkdir "${1%/*}" ||return $?  # so the line doesn't return an error.
    touch "${1}"
}

any way it is nearly always something that should be being done anyway.
It only the conditional one liners that tend to frustrate people a lot
from what I've seen.