UNIX for Dummies Questions & Answers

Yes that works. Thank you very much. Any idea why it can't all be on one line?

My limited experience of BSD sed is that it's a bit crude. Then on the other hand at one point it was pretty much the best definition of a standard.

Anyhow, to just avoid this whole syntactic morass, maybe it would be better (albeit marginally less efficient) to just use the following instead:

Code:

sed '42s/.*/I am the walrus/' file

That should basically work everywhere without modification.

The "c" command is part of POSIX sed.

Anytime you refer to GNU sed or GNU awk or GNU date you get nifty, new and non-standard ways of doing things. era's first example is pretty much GNU-only, the "two-line" thing is actually the old-fashioned standard. (see Dougherty & Robbins 'sed & awk' book) Meaning it is portable. If you work only on ubuntu or redhat you have GNU-derived tools. If you are on HPUX probably not.

It doesn't make anything here right or wrong, merely confusing for new people.
The authoritative answer is the man page on your machine.

The main portability hurdle here is whether or not c adds a trailing newline after the new text. It seems odd to me that it doesn't, but anyway, if you can't know, you'd better avoid the whole construct, or accept the fact that your script is specific to a particular class of sed implementations. But that way lies madness ...