You need to close the port I believe. <div> </div><div>Robby On Thursday, April 11, 2013, Steve Byan wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Section 3.7.4 "Regexp Matching" of the "Racket Reference" says in part: "If the optional output-port is provided as an output port, the part of input from its beginning (not start-pos) that precedes the match is written to the port. All of input up to end-pos is written to the port if no match is found. This functionality is most useful when input is an input port." Given this input file: multivac:~ smb$ cat /Users/smb/Library/Mail/V2/Mailboxes/personal.mbox/PMRC.mbox/Info.plist <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "<a href="http://www.apple.com/DTDs/PropertyList-1.0.dtd" target="_blank">http://www.apple.com/DTDs/PropertyList-1.0.dtd</a>"> <plist version="1.0"> <dict> <key>DisplayInThreadedMode</key> <string>no</string> <key>MailboxName</key> <string>PMRC</string> <key>SearchSortDescending</key> <string>YES</string> <key>SearchSortOrder</key> <string>received-date</string> <key>SortOrder</key> <string>received-date</string> <key>SortedDescending</key> <string>NO</string> </dict> </plist> I expect the following racket function to copy the entire input port to the output port: #lang racket (define (plist-file-match-sorted-descending plist-path) (let ([input-port (open-input-file plist-path)] [output-port (open-output-file (path-replace-suffix plist-path ".plist~") #:exists 'replace)]) (if (regexp-match "<key>SortedDescending</key>\n\t<string>YES</string>" input-port 0 #f output-port) (displayln "sorted descending") (displayln "sorted ascending")))) (define test-path (string->path "/Users/smb/Library/Mail/V2/Mailboxes/personal.mbox/PMRC.mbox/Info.plist")) I apply the function to the file path: Welcome to DrRacket, version 5.3.3 [3m]. Language: racket; memory limit: 128 MB. > (plist-file-match-sorted-descending test-path) sorted ascending > But despite my expectations the resulting Info.plist~ file is empty: multivac:~ smb$ ls -l /Users/smb/Library/Mail/V2/Mailboxes/personal.mbox/PMRC.mbox/Info.plist~ -rw-r--r-- 1 smb staff 0 Apr 10 17:09 /Users/smb/Library/Mail/V2/Mailboxes/personal.mbox/PMRC.mbox/Info.plist~ What am I missing? Best regards, -Steve -- Steve Byan <<a href="javascript:;" onclick="_e(event, 'cvml', 'stevebyan@me.com')">stevebyan@me.com</a>> Littleton, MA 01460 ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div>