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:
