Variable incremented in bash while loop resets to 0 when loop finishes [duplicate] - bash

Question

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Local variables after loop exit
(5 answers)
Closed 6 years ago.
I'm writing a bash script that uses a while loop to process over the rows outputted from a specific command. I also increment a variable (adding 1) for each row found.
Heres an example of the section of the script in question:
#!/bin/bash
count=0
ls | while read f
do
count=$(($count+1))
echo "Count is at ${count}"
done
echo "Found total of ${count} rows"
Basically, it increments the $count variable just fine, but then when I print $count after the while loop.. its reset to 0..
Example output:
Count is at 1
Count is at 2
Count is at 3
Count is at 4
Count is at 5
Found total of 0 rows
Any idea why the $count would reset after the loops done?
I also tried adding the last echo statement using the && operator on the loop, like so:
count=0
ls | while read f
do
count=$(($count+1))
echo "Count is at ${count}"
done && echo "Found total of ${count} rows"
With no success.
Any help would be appreciated

Answer 1

A pipe spawns a subshell, use a process substitutions instead:
while read -r f
do
count=$(($count+1))
echo "Count is at ${count}"
done < <(ls)
Also note that you shouldn't parse the output of ls.
And your example seems to count numbers of files and directories in current directory, which can be done with find and wc:
find -maxdepth 1 -mindepth 1 -printf "\n" | wc -l
or you can avoid ls with a for loop and globbing:
for f in * .*; do
[ -e "$f" ] || continue
count=$((count + 1))
echo "Count is at ${count}"
done