TranslateProject/sources/Linux Terminal--Seeing the unseen characters with cat!.md

(runningwater认领) Linux Terminal: Seeing the unseen characters with cat!

Sometimes a program or software don’t start for a syntax error, and if you check the files there is nothing wrong..apparently. There are a lot of characters that usually are not printed if you use a normal text editor, but you can easily check if they are present with your terminal and the command cat.

As first thing let’s create a simple text file with these special characters, open a terminal and run the command:

printf 'testing\012\011\011testing\014\010\012more testing\012\011\000\013\000even more testing\012\011\011\011\012' > /tmp/testing.txt

Now if you open the file with an editor you’ll have different results. A simple cat will show:

$ cat /tmp/testing.txt 
testing
		testing
 
more testing
 
even more testing

While if you open it with nano or vim you’ll see :

testing
            testing^L^H

more testing
    ^@^K^@even more testing

Now we can see some options of cat to print special characters.

1. Use cat -T to display TAB characters as ^I

   cat -T /tmp/testing.txt testing ^I^Itesting

   more testing ^I even more testing ^I^I^I

2. Use cat -E to display $ at end of each line

   $ cat -E /tmp/testing.txt testing$ testing $ more testing$

   even more testing$ $

3. Use a simple cat -A to show up all the invisible characters:

   $ cat -A /tmp/testing.txt testing$ ^I^Itesting^L^H$ more testing$ ^I^@^K^@even more testing$ ^I^I^I$

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via: http://linuxaria.com/pills/linux-terminal-seeing-the-unseen-characters-with-cat?lang=en#more-7645

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译者：runningwater 校对：校对者ID