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Programming Exercise A for RWET
RWET Programming Exercise A
Text processing on the UNIX command line
---
Step 1. Write the command to download the text file with the following URL to
your computer with the filename "frost.txt". (Hint: You'll need to use the
"curl" command, and possibly redirection with ">").
Here's the URL:
http://rwet.decontextualize.com/texts/frost.txt
Write the command here:
curl -O http://rwet.decontextualize.com/texts/frost.txt (with output on the screen)
curl http://rwet.decontextualize.com/texts/frost.txt >frost.txt (without output on the screen)
(This command will print no output to the screen.)
---
Step 1a. Verify step 1 by typing the following command:
$ cat <frost.txt
You should see the following:
Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,
And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.
I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I—
I took the one less travelled by,
And that has made all the difference.
---
Step 2. Write a command that displays the only the lines from frost.txt
that contain the string "And".
grep And frost.txt
You should see the following:
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
And having perhaps the better claim,
And both that morning equally lay
And that has made all the difference.
---
Step 3. Using a pipe, write a command that extracts the second word from
each of the lines you displayed in Step 3. (Hint: Use the "cut" command.)
grep And frost.txt|cut -d ' ' -f 2
You should see the following:
sorry
be
looked
having
both
that
---
Step 4. Add one more element to the pipe in step 3, so that the words are
displayed in alphabetical order.
grep And frost.txt|cut -d ' ' -f 2|sort
You should see the following:
be
both
having
looked
sorry
that
---
Step 5. We didn't talk about "fold" in class, but it's a useful command for
word-wrapping text. Investigate the "fold" command with "man" (type "man fold")
and write a command below to word-wrap "frost.txt" at 20 characters, keeping
word boundaries intact.
fold -s -w 20 frost.txt
Your output should look like this:
Two roads diverged
in a yellow wood,
And sorry I could
not travel both
And be one
traveler, long I
stood
And looked down one
as far as I could
To where it bent in
the undergrowth;
Then took the
other, as just as
fair,
And having perhaps
the better claim,
Because it was
grassy and wanted
wear;
Though as for that
the passing there
Had worn them
really about the
same,
And both that
morning equally lay
In leaves no step
had trodden black.
Oh, I kept the
first for another
day!
Yet knowing how way
leads on to way,
I doubted if I
should ever come
back.
I shall be telling
this with a sigh
Somewhere ages and
ages hence:
Two roads diverged
in a wood, and I—
I took the one less
travelled by,
And that has made
all the difference.
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