#!/bin/sh -u
#  $0  (no args)
# A script that loops appending some text to a file until the number of
# lines in the file is larger than a desired length.
#
# Some of the comments in this script are "teacher" comments that should
# never appear in student programs (or real-world programs).
#
# -IAN! idallen@ncf.ca  February 2002

export PATH=/bin:/usr/bin
umask 022

# The line to put into the output file.
# - note how the string is quoted to include protected blanks and newlines!
# The desired length of the output file, in lines.
# The name of the output file.
#
string='Hello World!
It is a Beautiful Day!'
numlines=12
file='myout.txt'

# Use command substitution to get the current length of the file.
# (Warning: Use  wc -l <"$file"  and not  wc -l "$file"  !)
# The output of "wc" (the single number) is substituted into the line.
# The "test" command (named "[") tests the number against the length.
# The return code of "test" determines whether the "while" keeps going.
#
>"$file"     # start with an empty output file
while [ $(wc -l <"$file") -lt $numlines ]; do
	echo "The current number of lines in '$file' is $(wc -l <"$file")"
	echo "$string" >>"$file"
	echo "    The new number of lines in '$file' is $(wc -l <"$file")"
done

echo "The number of lines in the output file is: $(wc -l <"$file")"
echo "The first four lines are"
head -4 "$file"

exit 0