bash check all file in a directory for their extension - bash

Question

I am writing a shell script to read all the files in the give directory by the user input then count how many files with that extension. I just started learning Bash and I am not sure why it this not locating the files or reading the directory. I am only putting 2 example but my count is always 0.
This is how I run my script
$./check_ext.sh /home/user/temp
my script check_ext.sh
#!/bin/bash
count1=0
count2=0
for file in "ls $1"
do
if [[ $file == *.sh ]]; then
echo "is a txt file"
(( count1++ ))
elif [[ $file == *.mp3 ]]; then
echo "is a mp3 file"
(( count2++ ))
fi
done;
echo $count $count2

Answer 1

"ls $1" doesn't execute ls on $1, it just a plain string. Command substitution syntax is $(ls "$1")
However there is no need to use ls, just use globbing:
count1=0
count2=0
for file in "$1"/*; do
if [[ $file == *.sh ]]; then
echo "is a txt file"
(( count1++ ))
elif [[ $file == *.mp3 ]]; then
echo "is a mp3 file"
(( count2++ ))
fi
done
echo "counts: $count1 $count2"
for file in "$1"/* will iterate through all the files/directories in the directory denoted by $1
EDIT: For doing it recursively inside a directory:
count1=0
count2=0
while IFS= read -r -d '' file; do
if [[ $file == *.sh ]]; then
echo "is a txt file"
(( count1++ ))
elif [[ $file == *.mp3 ]]; then
echo "is a mp3 file"
(( count2++ ))
fi
done < <(find "$1" -type f -print0)
echo "counts: $count1 $count2"

Answer 2

POSIXly:
count1=0
count2=0
for f in "$1"/*; do
case $f in
(*.sh) printf '%s is a txt file\n' "$f"; : "$((count1+=1))" ;;
(*.mp3) printf '%s is a mp3 file\n' "$f"; : "$((count2+=1))" ;;
esac
done
printf 'counts: %d %d\n' "$count1" "$count2"

Answer 3

You can use Bash arrays for this too: if you only want to deal with extensions sh and mp3:
#!/bin/bash
shopt -s nullglob
shs=( "$1"/*.sh )
mp3s=( "$1"/*.mp3 )
printf 'counts: %d %d\n' "${#shs[#]}" "${#mp3s[#]}"
If you want to deal with more extensions, you can generalize this process:
#!/bin/bash
shopt -s nullglob
exts=( .sh .mp3 .gz .txt )
counts=()
for ext in "${exts[#]}"; do
files=( "$1"/*."$ext" )
counts+=( "${#files[#]}" )
done
printf 'counts:'
printf ' %d' "${counts[#]}"
echo
If you want to deal with all extensions (using associative arrays, available in Bash ≥4)
#!/bin/bash
shopt -s nullglob
declare -A exts
for file in "$1"/*.*; do
ext=${file##*.}
((++'exts[$ext]'))
done
for ext in "${!exts[#]}"; do
printf '%s: %d\n' "$ext" "${exts[$ext]}"
done