Shell Programming and Scripting

# Set <tab> and <space> as field separators
awk -F'[\t ]' '
	# If NF (number of fields) in current input record == 1, set ofile variable = $1 (output filename)
	# next forces awk to immediately stop processing current record and go on to the next record
        NF == 1 {
                ofile = $1
                next
        }
	# If NF (number of fields) in current input record = 2, write record to ofile (output filename)
        NF == 2  {
                print $2 > ofile
        }
' input.txt

awk '	# Name utility used to run this script and open the script.
NF == 0 {
	# If this is a blank line (i.e., # of fields is zero), skip to next line
	# of input.
	next
}
!/^[ \t]/ {
	# if the first character on the line is not a <space> or a <tab>...
	# If the current output filename is not the empty string, close the
	# current output file.
	if(out_file)	close(out_file)
	# Set the name of the output file to use on the followng lines.
	out_file = $1
	# Skip to the next llne of input.
	next
}
{	# Print the current data (assumed to be a single word) to the current
	# output file, skipping leading <space> and <tab> characters...
	print $1 > out_file
	# Note that the above replaces existing input files with new contents
	# every time a new filename is encountered.  If you want to append
	# (instead of replace), change ">" to ">>".
}' input.txt	# Close the script and name the input file(s) to be processed.