you know you want to - Technomancy

Sandy – 2007-07-20T11:35:48Z: On Windows
Noah Slater – 2007-07-20T15:17:54Z: This example has two major errors.

Firstly, you need to quote the argument to sed or you will get a "sed: -e expression #1, char 21: unterminated `s' command" error.

Secondly, you cannot use sed to read from a while while concurrently writing to the same file. You need to use a temporary file in this instance.

A working script would look something like:

temporary_file=$(tempfile)

if [ $? -ne 0 ]; then

echo "Could not create temporary file.";

else

sed "s/localhost/localhost lolcathost/" /etc/hosts > $temporary_file;

mv $temporary_file /etc/hosts

fi
Phil – 2007-07-20T16:54:30Z: Thanks Noah. It was working for me when I piped the output to /etc/hosts2, but shame on me for not testing it all the way through. I also escaped the space, but my blogging software must have munched it.

Perhaps the pithiness of the original could be retained if it were ported to Ruby.
Fnor – 2007-07-20T17:00:06Z: You can also use the -i option of sed to edit in place instead of redirecting to a temporary file : )
Noah Slater – 2007-07-20T17:58:39Z: Aha, but the "-i" option is not portable. Heh.
Noah Slater – 2007-07-20T18:45:25Z: Aha, but the "-i" option is not portable. Heh.
Noah Slater – 2007-07-20T18:46:22Z: Your blogging software should do a redirect after the POST to avoid duplicate submissions by pressing "refresh".
Fnor – 2007-07-20T19:22:32Z: You can also use the -i option of sed to edit in place instead of redirecting to a temporary file : )
Fnor – 2007-07-20T19:25:01Z: Yes, I do agree for the redirect!

And thanks for the portability information.
Phil – 2007-07-21T00:17:33Z: Noted re: redirects. There's a lot of things this blog software should do. =)

Updated the example; thanks.

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