Let's say I start with just item1=('item1' '1' '20')
I then define itemnumber=2
I would like to create the next array as item$itemnumber=('item2' '4' '77'), but I get a syntax error.
After that I would like to just do itemnumber=$((itemnumber+1)), and create item$itemnumber=('item3' '17' '15')
Which would give me three arrays item1, 2 and 3:
item1=('item1' '1' '20')
item2=('item2' '4' '77')
item3=('item3' '17' '15')
Is this possible?
A task for eval:
itemnumber=1
(( itemnumber += 1))
eval "item$itemnumber=('item$itemnumber' '4' '77')"
eval echo \${item$itemnumber[*]}
Use the declare command, although you'll need to modify how you perform the assignment.
declare -a "item$itemnumber"
declare "item$itemnumber+=(item$itemnumber 4 77)
In bash 4.3, this is greatly simplified with named references.
itemnumber=0
declare -n arr=item$itemnumber
arr+=(item$itemnumber 1 20)
((itemnumber++))
declare -n arr=item$itemnumber
arr+=(item$itemnumber 4 77)
((itemnumber++))
declare -n arr=item$itemnumber
arr+=(item$itemnumber 17 15)
Just increment itemnumber, reset the reference, then use the reference as you would the actual array.
A bit late answer, but if you need this many times, you can use an function for assign
#!/bin/bash
assign () { eval "$1=($(printf '"%s" ' "$@"))"; }
itemnum=0
assign item$((++itemnum)) 1 2 3 4
assign item$((++itemnum)) 'q w e r'
assign item$((++itemnum)) a "$itemnum cc" dd
#show the array members enclosed in ''
echo "item1:" $(printf "'%s' " "${item1[@]}")
echo "item2:" $(printf "'%s' " "${item2[@]}")
echo "item3:" $(printf "'%s' " "${item3[@]}")
prints
item1: 'item1' '1' '2' '3' '4'
item2: 'item2' 'q w e r'
item3: 'item3' 'a' '3 cc' 'dd'
or simple
echo ${item1[@]}
echo ${item2[@]}
echo ${item3[@]}
prints
item1 1 2 3 4
item2 q w e r
item3 a 3 cc dd
if you want exclude, the first element from the array (the itemname), use
assign () { var="$1"; shift 1; eval "$var=($(printf '"%s" ' "$@"))"; }
n=0
assign item((++n)) 1 2 3 4
echo "item1 contains only: $item1[@]}"
prints
item1 contains only: 1 2 3 4
In bash 4.3, a namevar is the perfect tool:
set_item() {
local itemnumber=$1; shift
local -n array_name="item$itemnumber"
array_name=( "$@" )
}
set_item 2 1 2 3 4
set_item 3 2 3 4 5
...will have the same effect as...
item2=( 1 2 3 4 )
item3=( 2 3 4 5 )
namevarfeature (borrowed from ksh) which allows a more robust implementation.