Changes

# Issue the following linux command (using extended regular expression symbols) to display only whole numbers (with or without a positive or negative sign):<br><span style="color:blue;font-weight:bold;font-family:courier;">grep "^[+-]{0.1}[0-9]{1,}$" numbers2.dat | more</span><br><br>'''NOTE:''' most likely, there were NO results. This is due to the fact that the grep command was NOT issued correctly to use extended regular expression symbols. You would need to issue either '''grep -E''' (or more simply) issue the '''egrep''' command. The egrep command works with all regular expression symbols, and should be used in the future instead of the older grep command.<br><br>

# Reissue the above command using '''egrep''' instead of ''grep'':<br><span style="color:blue;font-weight:bold;font-family:courier;">egrep "^[+-]{0,1}[0-9]{1,}$" numbers2.dat | more</span><br><br>You should have noticed that the command worked correctly this time because you used the '''egrep''' command.<br><br>

=INVESTIGATION 3: OTHER COMMANDS THAT USE REGULAR EXPRESSIONS =