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By Root 1571 0

a noninteractive alternative, though, so you can still use them. For instance, if you wanted to call top, you could call it in a noninteractive form such as top -l1 and parse the result. The following (rather silly) example converts a number to a hex string by way of bc by writing out a small bc program file and calling bc to process it:

set theNum to text returned of (display dialog "Enter a number:" default answer "")

set t to path to temporary items

set posixT to POSIX path of t

set f to open for access file ((t as string) & "bctemp") with write permission

write "obase = 16\n" to f

write (theNum as string) & "\n" to f

write "quit\n" to f

close access f

set s to "/usr/bin/bc " & quoted form of (posixT & "bctemp")

display dialog (do shell script s)

(The text returned of display dialog is Unicode text in Tiger; I don't want to write Unicode text to the file, because bc won't be able to read it, so I coerce to a string.)

The Unix shell parsing and quotation rules can be something of a headache. A simple solution is to protect a string from the parsing rules completely by wrapping it in single quotes; AppleScript makes this easy with the quoted form property of a string (see "String Properties" in Chapter 13). But this does not absolve you from AppleScript's own rules for forming literal strings (see Table 13-1). So, for instance, in the system attribute example in "File and Machine Information" in Chapter 21, quotes are escaped in the literal string s, to get AppleScript to do the right thing; then the entire string is munged with quoted form to get the shell to do the right thing.

Using a file as an intermediary can simplify things. When talking to Perl, for example, there is no problem forming a short Perl script and handing it to Perl directly by means of the -e switch; but for a longer Perl script it might make sense to write it into a file and then tell Perl to run the file. The Perl script can be created on the fly, but often there is no need; it might make more sense to prepare it beforehand.

Here's an example. I write for the weekly online Macintosh journal TidBITS , whose archives are searchable online: their web site has a page (http://db.tidbits.com) where you can enter words to search for, returning a page of links to past articles containing those words. We'll simulate this page, acting as a web client ourselves, with the help of curl (a brilliant Internet client Unix tool—read the man pages for more information). We have researched the HTML format of the results page, and we've prepared a Perl script to parse it and extract the URLs and titles of the found articles. The Perl script expects as argument the pathname of the file containing the HTML:

$s = "";

while (<>) {

$s .= $_;

}

$s =~ m{search results (.*)$}si;

$1 =~ m{}si;

@rows = ($1 =~ m{}sig);

for ($i=0;$i<$#rows;$i++) {

($links[$i], $titles[$i]) =

($rows[$i+1] =~ m{(.*?)}i);

}

print join "\n", @links, @titles;

Now for the AppleScript code. First we put up a dialog where the user can enter the terms to search for. We URL-encode these terms in a primitive way (substituting a plus sign for any spaces) and assemble the post data for the form submission. We use curl to submit this post data to the TidBITS server. The TidBITS server receives essentially the same HTML it would receive if a user entered the same search terms in the first field of the TidBITS search page and pressed the Submit button. The results come back as a page of HTML, which curl writes out to a file. We now hand this file over to our Perl script for parsing. The results come back from the Perl script, and now we have a list which is really two lists: first the URLs of the found pages, then the titles of those same pages. We put up a list showing the titles; if the user chooses one, we ask the browser to display the corresponding URL.

set t to text returned of ¬

(display dialog "Search TidBITS for:" default answer "")

set text item delimiters to "+"

set t to (words of t) as string

set d to "'-response=TBSearch.lasso&-token.srch=TBAdv"