#!/bin/ksh
# Usage: lctoday file...
# This script will evaluate the pathnames given as operands and use "wc -l" to
# count lines in any of them that are regular files creater or modified at or
# after midnight today.  The total number of lines found will be printed to
# standard output.

# Initialize variables:
IAm=${0##*/}                    # This script's name
tmpf=${TMPDIR:-/tmp}/today.$$   # File with timestamp set to midnight today
unset list                      # initialize list of files to process

# Verify that we have at least one operand:
if [ $# -lt 1 ]
then    printf "Usage: %s file...\n" "$IAm" >&2
        exit 1
fi

# Create a temp file with midnight this morning as its timestamp:
if ! eval $(date '+touch -t %Y%m%d0000') "$tmpf"
then    printf "%s: Could not create file marking midnight" "$IAm" >&2
        exit 1
fi

# Select regular files with today's timestamp from the given pathname operands:
for i in "$@"
do      if [ -r "$i" ] && [ -f "$i" ] && [[ ! "$i" -ot "$tmpf" ]]
        then    # We have a readable regular file that was created or modified
                # today.
                list[${#list[@]}]="$i"  # Add it to the array of files to count.
        fi
done

# We have our list, get the line count of all of the files in the list.
wc -l "${list[@]}" /dev/null | {
        # If there is more than one file in the list, the last line wc prints
        # will be a total for all files processed and the word "total".  If
        # there is only one file, the only liee wc prints will contain the
        # total for that file and the filename.  Either way, we just need to
        # save the 1st word from the last line.
        # The /dev/null operand protects us if a single file is given and its
        # pathname contains a newline character, and gets rid of a special case
        # that would be otherwise needed if no files are selected.
        while read -r count other
        do      sum=$count
        done
        # Print the total number of lines reported by wc.
        echo $sum
}

# Cleanup.  Remove the temp file we created:
rm "$tmpf"

chmod +x lctoday

./lctoday *.txt

./lctoday c90.txt n5.txt t1.txt k3.txt h9.txt s1.txt n2.txt a123.txt