What commands can you use to determine who is logged in on a specific terminal?
How can you keep other users from using write to communicate with you? Why would you want to?
What happens when you give the following commands if the file named done already exists?
$ cp to_do done $ mv to_do done
How can you find out which utilities are available on your system for editing files? Which utilities are available for editing on your system?
How can you find the phone number for Ace Electronics in a file named phone that contains a list of names and phone numbers? Which command can you use to display the entire file in alphabetical order? How can you remove adjacent duplicate lines from the file? How can you remove all duplicates?
What happens when you use diff to compare two binary files that are not identical? (You can use gzip to create the binary files.) Explain why the diff output for binary files is not the same as the diff output for ASCII files.
Create a .plan file in your home directory. Does finger on your system display the contents of your .plan file?
What is the result of giving the which utility the name of a command that resides in a directory that is not in your search path?
Are any of the utilities discussed in this chapter found in more than one directory on your system? If so, which ones?
Experiment by calling the file utility with names of files in /usr/bin. How many different types of files are there?
Which command can you use to look at the first few lines of a file named status.report? Which command can you use to look at the end of the file?