Bash- Count Newlines via terminal command - linux

Question

i'm trying to make a bash script that counts the newlines in an input. The first if statement (switch $0) works fine but the problem I'm having is trying to get it to read the WC of a file in a terminal argument.
e.g.
~$ ./script.sh
1
2
3
4
(User presses CTRL+D)
display word count here # answer is 5 - works fine
e.g.
~$ .script1.sh < script1.sh
WC here -(5)
~$ succesfully redirects the stdin from a file
but
e.g.
~$ ./script1.sh script1.sh script2.sh
WC displayed here for script1.sh
WC displayed here for script2.sh
NOTHING
~$
the problem I believe is the second if statement, instead of executing the script in the terminal it goes to the if statement and waits for a user input and its not giving back the echo statement.
Any help would be greatly appreciated since I cannot figure out why it won't work without the ~$ < operator.
#!/bin/bash
#!/bin/sh
read filename ## read provided filename
USAGE="Usage: $0 $1 $2..." ## switch statement
if [ "$#" == "0" ]; then
declare -i lines=0 words=0 chars=0
while IFS= read -r line; do
((lines++))
array=($line)
((words += ${#array[#]}))
((chars += ${#line} + 1)) # add 1 for the newline
done < /dev/stdin
fi
echo "$lines $words $chars $filename" ## filename doesn't print, just filler
### problem if statement####
if [ "$#" != "0" ]; then # space between [] IS VERY IMPORTANT
declare -i lines=0 words=0 chars=0
while IFS= read -r line; do
lines=$( grep -c '\n'<"filename") ##should use grep -c to compare only new lines in the filename. assign to variable line
words=$( grep -c '\n'<"filename")
chars=$( grep -c '\n'<"filename")
echo "$lines $words $chars"
#lets user press CTRL+D to end script and count the WC
fi

Answer 1

#!/bin/sh
set -e
if [ -t 0 ]; then
# We are *not* reading stdin from a pipe or a redirection.
# Get the counts from the files specified on the cmdline
if [ "$#" -eq 0 ]; then
echo "no files specified" >&2
exit 1
fi
cat "$#" | wc
else
# stdin is attached to a pipe or redirected from a file
wc
fi | { read lines words chars; echo "lines=$lines words=$words chars=$chars"; }
The variables from the read command only exist within the braces, due to the way the shell (some shells anyway) use subshells for commands in a pipeline. Typically, the solution for that is to redirect from a process substitution (bash/ksh).
This can be squashed down to
#!/bin/bash
[[ -t 0 ]] && files=true || files=false
read lines words chars < <({ ! $files && cat || cat "$#"; } | wc)
echo "lines=$lines words=$words chars=$chars"
a very quick demo of cmd | read x versus read x < <(cmd)
$ x=foo; echo bar | read x; echo $x
foo
$ x=foo; read x < <(echo bar); echo $x
bar

Answer 2

Use wc.
Maybe the simplest is to replace the second if block with a for.
$: cat tst
#! /bin/env bash
declare -i lines=0 words=0 chars=0
case "$#" in
0) wc ;;
*) for file in $*
do read lines words chars x <<< "$( wc $file )"
echo "$lines $words $chars $file"
done ;;
esac
$: cat foo
hello
world
and
goodbye cruel world!
$: tst < foo
6 6 40
$: tst foo tst
6 6 40 foo
9 38 206 tst