comment on 1st week rush, hw1

show last night's 90min effort

fill in gaps:  get vs. post:  

	secure vs. open, 
	automatic subfunction naming/linking,
	stdin parsing help vs. failure-to-reset bugs,
	cleanliness to user vs. robot/spider access
	can't use both at same time 
		(unless browser is nonstandard)
	can use ENVIRON cookies and post at same time
	can have a script which responds to both 
		(invoke with form/post or URL/get)

debugging hints:

	print your data as it arrives, then exit
	note special characters in your data
	test for syntax errors on server at command line
		(if no bad side effects)
	hr is a good tag for reading debugging output sent to browser
	put Content-type right at top
	print to a public-writeable dir/file, 
		print "got here" > "/tmp/cgi.debug"
	when in doubt, make your own 
		echo > cgi.debug; chmod a+rw cgi.debug
	always view the source of the cgi output (could be html bug!)
	check /var/log/http/error_log 
		(how?  less error_log, shift-G, ctrl-B) 
	DO write little t.awk scripts to test semantics

gawk help:

	what is RS, FS?
	rsfs.awk
	what is an associative array? 
		for (i in a)
		a[s]
		if (s in a)
		if (a[s])
		string context of an index
		a[x,y]
	array.awk
	array2.awk
	what is the semantics of $i?  
		read sets $0, $1...$NF, NF 
		assignment to $i causes lazy evaluation of $0
		with possible side effects on $(i+1), ...$NF, NF)
	what is gsub(r,s,t)?
		r=regexp
		s=subst
		t=target
		how to verify this quickly?
			man gawk
			/gsub\(
			man gawk | grep gsub
			my link to subman!
	translating special characters, +/space, %22/quote
		data = ENVIRON["QUERY_STRING"]; clean(data)
		func clean(x) {
		  gsub("%22","\"",x)
		  return x 
	 	}

parsing multi-field input:  ok?

saving state:
	in cookies:  
		Set-Cookie: foo=val; foo2=val2; expires=date
		ENVIRON["HTTP_COOKIE"]
		spec.cgi
	much better in forms: 
		input type=hidden name=foo value=bar
	even better with server-side files:
		make sure your file is chmod a+rw
		grepdat.cgi

security:
	if you execute data using system or "com" | getline,
	YOU MUST (1) translate selective characters OR
	(2) handle ALL user data within ''
	grepcgi.cgi

example/lab:
	saving data on the server side for search and dbase