I tried the += operator to append an array in bash but do not know why it did not work
#!/bin/bash
i=0
args=()
while [ $i -lt 5 ]; do
args+=("${i}")
echo "${args}"
let i=i+1
done
expected results
0
0 1
0 1 2
0 1 2 3
0 1 2 3 4
actual results
0
0
0
0
0
Any help would be appreciated.
It did work, but you're only echoing the first element of the array. Use this instead:
echo "${args[@]}"
Bash's syntax for arrays is confusing. Use ${args[@]}
to get all the elements of the array. Using ${args}
is equivalent to ${args[0]}
, which gets the first element (at index 0).
See ShellCheck : Expanding an array without an index only gives the first element.
Also btw you can simplify let i=i+1
to ((i++))
, but it's even simpler to use a C-style for
loop. And also you don't need to define args
before adding to it.
So:
#!/bin/bash
for ((i=0; i<5; ++i)); do
args+=($i)
echo "${args[@]}"
done
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