Bash add array string suffix to an array

user_17580101 0
Viewed 102

I have two bash arrays, and I want to append array strings to the end of the name array elements.

array=(a b c)
name=(toto_ tata_)

result :

toto_a
toto_b
toto_c
tata_a
tata_b
tata_c

I tried those command :

for i in "${name[@]}"
do
    arra=( "${i/%/$array[@]}" )
done
printf '%s\n' "${arra[@]}"
loops bash
3 Answers

Using Brace Expansion to expand as a cross-product

readarray -t new_array < <(IFS=,; eval "printf '%s\n' {${name[*]}}{${array[*]}}")
# ....................................................^..........^^...........^

then

$ declare -p new_array
declare -a new_array=([0]="toto_a" [1]="toto_b" [2]="toto_c" [3]="tata_a" [4]="tata_b" [5]="tata_c")

Eval is necessary to allow the variable expansion to occur first, then perform the brace expansion second.

user_75520

I'd recommend using a second for:

array=(a b c)
name=(toto_ tata_)
arra=()

for i in "${name[@]}"; do
    for j in "${array[@]}"; do
        arra+=("$i$j")
    done
done
printf '%s\n' "${arra[@]}"

Will produce:

toto_a
toto_b
toto_c
tata_a
tata_b
tata_c

Try it online!

user_56255470

Second for could be avoided by Parameter expansion

for nam in "${name[@]}";do printf "${nam/%/%s\\n}" "${array[@]}";done

will produce:

toto_a
toto_b
toto_c
tata_a
tata_b
tata_c

For fun, some variants (without any for loop):

printf -v fmt "${name[*]/%/%%s\\n}"
printf "${fmt// }" ${array[@]}
toto_a
tata_b
toto_c
tata_

or

printf -v fmt "${name[*]/%/%%s\\n}";printf "${fmt// }" ${array[@]}{,}
toto_a
tata_b
toto_c
tata_a
toto_b
tata_c

then without for, but with a fork to sort

printf -v fmt "${name[*]/%/%%s\\n}";printf "${fmt// }" ${array[@]}{,} |
    sort -k 1r,1.5
toto_a
toto_b
toto_c
tata_a
tata_b
tata_c
user_17656580
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