Shell Programming and Scripting

So, I'm writing a shell script to help automate a process I'm doing. Basically I want to take input from the user for 2 variables, then create a file that consists of:

Code:

Variable1,Variable2
Constant1
Constant2
..
Constant2000

then run an awk script. I'm pretty new to unix though, and so far I've been creating new files by hitting ctrl-d at the end of my input, like so:

Code:

cat > script.awk
{
do stuff
}
(ctrl-d)

My google-fu is failing me. Is there a way I can tell the script "this is where the file you're making ends" without hitting ctrl-d? Really stupid question I know, but hopefully there's a simple answer!

ctrl-d is not a "cat" thing by the way, it's a terminal thing. It forces the terminal to send an end-of-file condition. If you do ctrl-d just at your prompt, it will probably log you out.

What you want sounds like a here-document. You can tell the shell to build a document and feed it into cat.

Code:

cat > outputfile <<EOF
line1
line2
line3
line with $variable in it
and other such stuff
EOF

Note that the ending EOF cannot be indented, it must be at the beginning of the line.

Code:

cat <<EOF > script.awk
{
do stuff
}
EOF

Yeah, I knew ctrl-d wasn't a cat thing. That's why I was pretty embarrassed by this post. But if you can't ask anonymous people on the internet, who can you ask? :P

There are some subtleties with regard to quoting, expansions, and leading tabs. I suggest you carefully read the relevant section of your shell's manual page.

Regards,
Alister

Thanks everybody, that worked like a charm. So while we're here, how should I be telling cat to end files if I'm just doing command line work besides ctrl-d?

If you want to use the terminal to send an end-of-file signal, that's what ctrl-d is for. You might be able to redefine it to another key if you really wanted, but it's what it is for.

If you want a better way to edit files, try an editor like vi, vim, pico, or nano.