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help with SEEK, TELL, READ, othersby Kozz (Friar) |
on Jun 29, 2000 at 04:55 UTC ( [id://20308]=perlquestion: print w/replies, xml ) | Need Help?? |
Kozz has asked for the wisdom of the Perl Monks concerning the following question:
Most wise monks: I'm having some difficulties. I want to open a file for read/write and immediately obtain an exclusive lock, read the whole thing into a scalar (or array), do something with the data I read, then write it all back to the file (clobbering whatever was once there), then close it. But how do I do all this? I thought I saw a good explanation in a post a week ago, but I couldn't find the post. And I also tried reading the manpages, but was unable to decipher all the functions. Perhaps I'm missing something. Here's what I've got: So the problem is that this seems to leave me with an empty file, rather than reading and then writing what I had. Perhaps I'm intermixing some seek/read/truncate calls incorrectly or something. In addition, if I simply want to read the entire file into the scalar using read(), how would I do that, since I don't know the length (in bytes) to ask for? Honestly, I did read some man pages for read, seek, truncate, tell, but I must be missing something, or making a blatantly obvious mistake. Any help you can provide is much appreciated. Thanks! --Kozz
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