What You Should Know From Lecture: Week 2

### Monday pt 2:

Text editors in the shell!

You nave all used ‘nano’, but lets just see what it does.

Remember that you can make an empty file using ‘touch’. First make a directory in week2_monday called file_test and cd into it.

[c177-i0@n2010 file_test]$ touch test.txt
[c177-i0@n2010 file_test]$ ls
test.txt
[c177-i0@n2010 file_test]$ rm test.txt
[c177-i0@n2010 file_test]$ ls
[c177-i0@n2010 file_test]$

Lets use nano to make test.txt

[c177-i0@n2010 file_test]$ nano test.txt

The empty file looks like this

GNU nano 2.0.9                           File: test.txt                                                              


















^G Get Help        ^O WriteOut        ^R Read File   ^Y Prev Page       ^K Cut Text        ^C Cur Pos
^X Exit            ^J Justify         ^W Where Is        ^V Next Page       ^U UnCut Text      ^T To Spell

On Hoffman2, if you exit ‘^X’ (control X) before writing any text, the file will not exist.

Try it again but this time add any thing, even a single space will create the file. Now when you exit (^X), nano will ask you to save changes (y/n), then it lets you know it is updating the file (but you can change the file name here if you want), and the you exit out of nano.

[c177-i0@n2010 file_test]$ nano test.txt
[c177-i0@n2010 file_test]$ ls
[c177-i0@n2010 file_test]$ wc -l test.txt
1 test.txt

Try opening test.txt in nano and adding five words across 2 lines. After you type ^X same this to a new file called this new file test_add.txt

The result should be something similar to the following:

[c177-i0@n2010 file_test]$ nano test.txt
[c177-i0@n2010 file_test]$ ls
test_add.txt  test.txt
[c177-i0@n2010 file_test]$ wc *
 2  5 26 test_add.txt
 1  0  3 test.txt
 3  5 29 total
[c177-i0@n2010 file_test]$ head test_add.txt
one two three
four five  
[c177-i0@n2010 file_test]$

There are other more complicated text editors available in the shell. Feel free to check them out: emacs and vi

There are other ways to make files. Lets try ‘echo’ first and ‘printf’ second.

[c177-i0@n2010 file_test]$ echo "I love dogs"
I love dogs

‘echo’ display a line of text. We can redirect that text to a file…

[c177-i0@n2010 file_test]$ echo "I love dogs" > dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs

‘printf’ does something similar. It formats and print data

[c177-i0@n2010 file_test]$ printf "cats are ok too"
cats are ok too[c177-i0@n2010 file_test]$

To get a newline we need to add the newline character ‘’

[c177-i0@n2010 file_test]$ printf "cats are ok too\n"
cats are ok too

We can redirect this text to a text file using ‘>>’

[c177-i0@n2010 file_test]$ printf "cats are ok too" >> dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs
cats are ok too[c177-i0@n2010 file_test]$

but don’t for get ‘’

[c177-i0@n2010 file_test]$printf "cats are ok too\n" >> dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs
cats are ok toocats are ok too

Note: we used ‘>>’ rather than ‘>’ and it added text to the end of the previous file text.

Lets add some more stuff.

[c177-i0@n2010 file_test]$ echo "I love dogs" >> dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs
cats are ok toocats are ok too
I love dogs
[c177-i0@n2010 file_test]$ printf "cats are ok too\t" >> dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs
cats are ok toocats are ok too
I love dogs
cats are ok too [c177-i0@n2010 file_test]$

We added a ‘’ to the ‘printf’ statement and it added a tab.

[c177-i0@n2010 file_test]$ printf "cats are ok too\n" >> dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs
cats are ok toocats are ok too
I love dogs
cats are ok too cats are ok too
[c177-i0@n2010 file_test]$

What happens if we add text with a ‘>’

[c177-i0@n2010 file_test]$ echo "I love dogs" > dogs.txt
[c177-i0@n2010 file_test]$ head dogs.txt
I love dogs

What You Should Know From Lecture: Week 2

### Monday pt 2:

Monday pt 2 Challenge