Counting the number of lines of many files (only .h, .c and .py files) in a directory using bash - bash

Question

I'm asked to write a script (using bash) that count the number of lines in files (but only C files (.h and .c) and python files (.py)) that are regrouped in a single directory. I've already tried with this code but my calculation is always wrong
let "sum = 0"
let "sum = sum + $(wc -l $1/*.c | tail --lines=1 | tr -dc '0-9')"
let "sum = sum + $(wc -l $1/*.h | tail --lines=1 | tr -dc '0-9')"
let "sum = sum + $(wc -l $1/*.py | tail --lines=1 | tr -dc '0-9')"
echo $sum >> manifest.txt
I must write the total in the "manifest.txt" file and the argument of my script is the path to the directory that contains the files.
If someone has another technique to compute this, I'd be very grateful.
Thank you !

Answer 1

You could also use a loop to aggregate the counts:
extensions=("*.h" "*.c" "*.py")
sum=0
for ext in ${extensions[#]} ; do
count=$(wc -l ${1}/${ext} | awk '{ print $1 }')
sum=$((sum+count))
done
echo "${sum}"

Answer 2

Version 1: step by step
#!/bin/bash
echo "Counting the total number of lines for all .c .h .py files in $1"
sum=0
num_py=$(wc -l $1/*.py | tail -1 | tr -dc '0-9')
num_c=$(wc -l $1/*.c | tail -1 | tr -dc '0-9')
num_h=$(wc -l $1/*.h | tail -1 | tr -dc '0-9')
sum=$(($num_py + $num_c + $num_h))
echo $sum >> manifest.txt
version 2: concise
#!/bin/bash
echo "Counting the total number of lines for all .c .h .py files in $1"
echo "$(( $(wc -l $1/*.py | tail -1 | tr -dc '0-9') + $(wc -l $1/*.c | tail -1 | tr -dc '0-9') + $(wc -l $1/*.h | tail -1 | tr -dc '0-9') ))" >> manifest.txt
version 3: loop over your desired files
#!/bin/bash
echo "Counting the total number of lines for all .c .h .py files in $1"
sum=0
for sfile in $1/*.{c,h,py}; do
sum=$(($sum+$(wc -l $sfile|tail -1|tr -dc '0-9')))
done
echo $sum >> manifest.txt
This is how arithmetic operations work: var = $((EXPR))
For example: $sum= $(($sum + $result ))
it is very common to miss the $ sign within the EXPR! Try not to forget them :)

Answer 3

This is the scripts that I use (with minor modifications):
files=( $(find . -mindepth 1 -maxdepth 1 -type f -iname "*.h" -iname "*.c" -iname "*.py") )
declare -i total=0
for file in "${files[#]}"; do
lines="$(wc -l < <(cat "$file"))"
echo -e "${lines}\t${file}"
total+="$lines"
done
echo -e "\n$total\ttotal"

Answer 4

Here is my version.
#!/usr/bin/env bash
shopt -s extglob nullglob
files=( "$1"/*.#(c|h|py) )
shopt -u extglob nullglob
while IFS= read -rd '' file_name; do
count=$(wc -l < "$file_name")
((sum+=count))
done< <(printf '%s\0' "${files[#]}")
echo "$sum" > manifest.txt
Needs some error checking, like if the argument is a directory or if it even exists at all, and so on.