SUSE LINUX Documentation - Index of

100 Start-Up
Viewing Files with Less and More
Linux includes two small programs for viewing text files directly in the shell: less
and more. Rather than starting an editor to read a file like Readme.txt, simply enter
less Readme.txt to display the text in the console window. Use Space to scroll
down one page. Use Page ↑ and Page ↓ to move forward or backward in the text. To
exit less, press Q .
Instead of less, you can also use the older program more. However, it is less convenient
because it does not allow you to scroll backwards.
The program less got its name from the the precept that less is more and can also be
used to view the output of commands in a convenient way. To see how this works, read
Section “Redirection and Pipes” (page 100).
Redirection and Pipes
Normally, the standard output in the shell is your screen or the console window and
the standard input is the keyboard. However, the shell provides functions by which you
can redirect the input or the output to another object, such as a file or another command.
With the help of the symbols > and file.txt. This creates a file named file.txt that contains
the list of contents of your current directory as generated by the ls command. However,
if a file named file.txt already exists, this command overwrites the existing file.
To prevent this, use >>. Entering ls -l >> file.txt simply appends the output
of the ls command to an already existing file named file.txt. If the file does not
exist, it is created.
Sometimes it is also useful to use a file as the input for a command. For example, with
the tr command, you can replace characters redirected from a file and write the result
to the standard output, your screen. Suppose you want to replace all characters t of
your file.txt from the example above with x and print this to your screen. Do so
by entering tr t x < file.txt.
Just like the standard output, the standard error output is sent to the console. To redirect
the standard error output to a file named errors, append 2> errors to the corre-