Prefix and postfix elements of a bash array

Question

I want to pre- and postfix an array in bash similar to brace expansion.

Say I have a bash array

ARRAY=( one two three ) 

I want to be able to pre- and postfix it like the following brace expansion

echo prefix_{one,two,three}_suffix 

The best I've been able to find uses bash regex to either add a prefix or a suffix

echo ${ARRAY[@]/#/prefix_} echo ${ARRAY[@]/%/_suffix} 

but I can't find anything on how to do both at once. Potentially I could use regex captures and do something like

echo ${ARRAY[@]/.*/prefix_$1_suffix} 

but it doesn't seem like captures are supported in bash variable regex substitution. I could also store a temporary array variable like

PRE=(${ARRAY[@]/#/prefix_}) echo ${PRE[@]/%/_suffix} 

This is probably the best I can think of, but it still seems sub par. A final alternative is to use a for loop akin to

EXPANDED="" for E in ${ARRAY[@]}; do     EXPANDED="prefix_${E}_suffix $EXPANDED" done echo $EXPANDED 

but that is super ugly. I also don't know how I would get it to work if I wanted spaces anywhere the prefix suffix or array elements.

Answer 1

Bash brace expansion don't use regexes. The pattern used is just some shell glob, which you can find in bash manual 3.5.8.1 Pattern Matching.

Your two-step solution is cool, but it needs some quotes for whitespace safety:

ARR_PRE=("${ARRAY[@]/#/prefix_}") echo "${ARR_PRE[@]/%/_suffix}" 

You can also do it in some evil way:

eval "something $(printf 'pre_%q_suf ' "${ARRAY[@]}")"