SED: How can I use -n and -f together

Question

I want to write a sed script where the echoing is off, like

#!/bin/sed -n -f
s/x/u/g

but that gives my an

Invalid option -- ' '

error.

How can I do this?

Answer 1

It's because you tried to pass more than one argument in the shebang. Compare:

• Multiple arguments in shebang
• Shebang line with #!/usr/bin/env command --argument fails on Linux

In this particular case you can compact -n -f to -nf. In general this is not always possible. Here the script will be:

#!/bin/sed -nf
s/x/u/g

^{Note: It seems to me the script in its current form will print nothing because of -n. I assume you're going to expand it.}