If you want to use a search string which consists of more than one word, en-
close the string in double quotation marks, for example:
grep "music is great" ~/*
17.9 Viewing Text Files
When searching for the contents of a le with grep, the output gives you the line in
which the searchstring was found along with the lename. Often this contextual
information is still not enough information to decide whether you want to open and
edit this le. Bash oers you several commands to have a quick look at the contents
of a text le directly in the shell, without opening an editor.
head
With head you can view the rst lines of a text le. If you do not specify the
command any further, head shows the rst 10 lines of a text le.
tail
The tail command is the counterpart of head. If you use tail without any further
options it displays the last 10 lines of a text le. This can be very useful to view
log les of your system, where the most recent messages or log entries are usu-
ally found at the end of the le.
less
With less, display the whole contents of a text le. To move up and down half a
page use [Page ↑] and [Page ↓]. Use [Space] to scroll down one page. [Home]
takes you to the beginning, and [End] to the end of the document. To end the
viewing mode, press [Q].
more
Instead of less, you can also use the older program more. It has basically the
same function—however, it is less convenient because it does not allow you to
scroll backwards. Use [Space] to move forward. When you reach the end of the
document, the viewer closes automatically.
cat
The cat command displays the contents of a le, printing the entire contents to
the screen without interruption. As cat does not allow you to scroll it is not very
useful as viewer but it is rather often used in combination with other commands.
17.10 Redirection and Pipes
Sometimes it would be useful if you could write the output of a command to a le
for further editing or if you could combine several commands, using the output of
one command as the input for the next one. The shell oers this function by means
of redirection or pipes.
Shell Basics 211
