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up vote 4 down vote favorite

I had a confusion with this topic between switching between command line and script file interface. I had a nice script written out in the command line that worked, but as soon as I wanted to save it to a .sed file, I remembered I could no longer use the -n. I tried using '!d' flag, but I'm not getting the same output. My question:
Is there a way to put the -n in a .sed file, or some other way to stop the automatic printing when I'm in script file interface? I hate to have to convert from protecting my script from the shell to not protecting it, but I guess there is no way around it?

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1  
This question would be much easier to understand with some specifics - are you saying you can't use the -n and -f command line options together for some reason? – steeldriver 8 hours ago
    
I'm wanting to stop automatic printing when I'm writing a .sed file. I have only used -n on the command line to do this. However, I'm unfamiliar with how to do this in a .sed file because we don't need to protect our sed script from the shell etc... Overall: how do I stop automatic printing when I'm writing a .sed file? – Nack 8 hours ago
1  
Are you planning to use the file with sed -f from the command line, or using #!/usr/bin/sed -f at the top of the file? Either way, replacing the -f with -nf should work. – Daniel H 7 hours ago
    
Yes, I plan on using 'sed -f myfile.sed filein' – Nack 7 hours ago
    
Yes, I need the whole script in the .sed file. Only thing on the command line should be 'sed -f myfile.sed filein'. I want to integrate the turning off the automatic printing in my .sed file, and not on the command line – Nack 7 hours ago
up vote 9 down vote accepted

The standard (POSIX) way is to have #n at the start of the script. They have to be the first two bytes of the script.

That precludes the use of a she-bang, that's only to be used for scripts run as sed -f the-script (note that she-bangs are not POSIX and POSIX doesn't specify the path of utilities), but as @Kusalananda said, when using a she-bang, you can always do:

#! /path/to/sed -nf

If you want to make an executable sed script on systems that support she-bangs with arguments (most).

Note that the #n also works on the command line as in:

sed '#n
  s/foo/bar/p'

And you can add more text after like:

#no default output
s/foo/bar/p

Or:

#nifty way to turn -n on
s/foo/bar/p

Actually, that's something to bear in mind to avoid turning -n on by mistake. It's a good idea to use a space after # in comments for that (and for legibility).

# no, I don't want to turn -n on
s/foo/bar/
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Might be worth pointing out that the #n doesn't replace the #! line for an executable sed script, and you can't use both. Hence a sed script with #n needs to be run with sed -f explicitly on the command line, as far as I can see at least. – Kusalananda 7 hours ago
up vote 2 down vote

sed [-e] 'command' and sed -f /path/to/script behave exactly the same way with respect to the -n switch. If you want to execute a sed script and turn off the "print-by-default" behavior, use sed -n -f /path/to/script.sed /path/to/input.

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up vote 2 down vote

You will either have to run the sed script using

$ sed -n -f script.sed

or change the #! ("hash-bang") line in the script to something like

#!/usr/bin/sed -nf

and run it with

$ ./script.sed
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