Bash idioms for conditional array append?


I am trying to figure out if there is a shorter way in bash of conditionally appending the value of a variable to an array only if the value is non-null.

I believe the following is correct, but kind of "wordy"


if [[ "${my_var:-}" ]]; then
    my_array+=( "${my_var}" )

I’m asking because I’m trying to clean up some code that does this instead:

my_array+=( ${my_var:-} )

which is a hack that "works" to conditionally append the value of my_var to my_array only if my_var is non-null, but has the problem that if the string in my_var contains a space (or whatever IFS is set to) it does something very unintended (appends multiple elements into the array).

I was thinking of this maybe, but I’m not sure if my intent is sufficiently clear.

[[ "${my_var:-}" ]] && my_array+=( "${my_var}" )

is there a way to conditionally append only non-null values that is terse but idiomatic and clear?

>Solution :

One option is

my_array+=( ${my_var+"$my_var"} )

That will add the value of my_var to the array if it is defined, even if it is empty. If you want to not add it if it is undefined or defined but empty use

my_array+=( ${my_var:+"$my_var"} )

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