array in loop in bash

Question

I try to make a pseudo array in bash

    frame1=(one two three)
    frame2=(one two three)
    frame3=(one two three)
    echo ${frame2[2]}

works but

for ((fr=1; fr<=$records; fr++)) 
do
frame$fr=(one two three)
done

doesn't work. How to make a pseudo array like that in bash ?

[edit] if I try to use the variable in the inside loop it doesn't work

for ((fr=0; fr<=$records; fr++))
do
declare -a "frame$fr=(one two three)"
done
for ((fr=0; fr<=$records; fr++))
do
for ((lv=0; lv<=$fields; lv++))
do
#echo ${frame$fr[2]}
echo ${frame6[$lv]}
done
done

the above works but the line that is commented out does not work it says

line 16: ${frame$fr[2]}: bad substitution

Re: your edit. You must use indirect expansion. Btw, Bash is not exactly supposed to work like this, with simili-pointers. Leave that for other programming languages and review your design. Now if you really want to do this, name=frame$fr[$lv]; echo "${!name}" will do. — gniourf_gniourf
– gniourf_gniourf, Commented Apr 29, 2014 at 16:19
I just try to get the fields (images) from a spreadsheet with awk and send them to an array and then to imagemagick. would you call #!/bin/awk a language ? can I send to imagemagick from awk ? otherwise what language would you suggest as I think I will get in trouble this way because I still have to put real values in the array. — user3585600
– user3585600, Commented Apr 29, 2014 at 17:23
You could try with Perl, as it has nice bindings for ImageMagick, and you'll be able to do arrays of arrays without problems. Python would be okay too. — gniourf_gniourf
– gniourf_gniourf, Commented Apr 29, 2014 at 17:41

chepner · Accepted Answer · 2014-04-29 14:18:43Z

1

Use the declare builtin to evaluate the LHS to a name first.

for ((f1=1; f2<=$records; fr++))
do
  declare -a "frame$fr=(one two three)"
done

answered Apr 29, 2014 at 14:18

chepner

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