Redirection doesn't show up as an argument to a sourced script

Question

My problem is that I can't print to the screen when I write a bash script

. myBashScript.sh < text.txt

In myBashScript.sh I just print out

echo $2

But instead of printing "text.txt", it show a 'newLine'. As I have been know that '<' is a new line.

Why is $2 not text.txt?

Answer 1

I assume you're actually typing

./myBashScript.sh < text.txt

with a forward slash.

When you run ./myBashScript.sh < text.txt, your interactive shell actually captures the < text.txt and interprets it as a special instruction – in particular, it interprets your command line to mean that it should run myBashScript.sh with standard input connected to text.txt. Your shell then removes < text.txt from the command line before passing off control to myBashScript.sh. So as far as your shell script is concerned, it receives zero arguments, and $2 is empty. Your script translates simply to

echo

which prints a newline.

If you want to actually print the name of the file, you should consider

#!/bin/sh
echo $1

which you can then run:

$ ./myShellScript text.txt
text.txt

If, on the other hand, you want to print the contents of the file, you should use cat(1); your shell script should be

#!/bin/sh
cat $1

which you can then run:

$ ./myShellScript text.txt
Hello from text.txt, a file containing a bunch of test strings.