Summary

In this chapter, you covered the following topics:

•  Listing files using ls

•  Viewing the content of a file using cat

•  Counting the words, lines, and characters in a file using wc

•  Copying files using cp

•  Renaming files using mv

•  Removing files using rm

Knowing how to perform each of these tasks is essential to becoming a good shell programmer. In the chapters ahead you use these basics to create scripts for solving real world problems.

Questions

1.  What are invisible files? How do you use ls to list them?

2.  Will there be any difference in the output of the following commands?

a.  $ ls -a1

b.  $ ls -1 -a

c.  $ ls -1a

3.  Which options should be specified to wc in order to count the number of lines and characters in a file?

4.  Given that hw1, hw2, ch1, and ch2 are files and book and homework are directories, which of the following commands generates an error message?

a.  $ cp hw1 ch2 homework

b.  $ cp hw1 homework hw2 book

c.  $ rm hw1 homework ch1

d.  $ rm hw2 ch2

Terms

ls

The command that lists the files in a directory.

cat

The command that views the contents of a file.

wc

The command that counts the words, lines, and characters in a file.

cp

The command that copies files.

mv

The command that renames files.

rm

The command that removes files.

Ordinary File

A file on the system that contains data, text, or program instructions.

Directories

A type of file that stores other files. For users familiar with Windows or Mac OS, UNIX directories are equivalent to folders.

Invisible Files or Hidden Files

Files whose names start with the . character. By default the ls command does not list these files. You can list them by specifying the -a option to ls.