Empty array after a while loop

Question

I'm trying to do something very simple that consists in insert a set of dates into an array. So I run a git command which wil return an one line result, from that result I'm getting the dates using awk. After I iterate over all dates and add them to the array. In the end, the array is still empty but if I print the array during the loop it seems to have data inside.

Why is the array empty after the loop?

git reflog --date=local <branch_name> | 
awk '{ print $3 " " $4 " " $5 }' | 
while read date; do a+=(`echo "$date"`); done; echo ${a[@]}

I understand that every command after a pipe is executed in a different subshell, but in this case I think it is not influencing the final result...

Since you are assigning a variable in a subshell, so the variable scope is the subshell and the parent can't see it. — drizzt
– drizzt, Commented Oct 16, 2014 at 16:24

Tom Fenech · Accepted Answer · 2014-10-16 17:32:16Z

4

Your while loop is running in a subshell, so the variable is out of scope after it finishes.

Since you are using bash you can use process substitution instead:

while read date; do 
    a+=( $(echo "$date") )
done < <(git reflog --date=local <branch_name> | awk '{ print $3 " " $4 " " $5 }')
echo "${a[@]}"

edited Oct 16, 2014 at 17:32

Tom Fenech

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answered Oct 16, 2014 at 16:21

drizzt

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1 Comment

Hugo Sousa Over a year ago

Oh god, so my supposition was completely wrong. It works. Thanks!

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