TCL Opinions wanted – file reading/writing

This topic has 8 replies, 5 voices, and was last updated 18 years, 7 months ago by Tom Patton.

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December 23, 2005 at 1:54 pm #48222

Anonymous
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I have an interface that I think I’m going to have to read/write to a file in the Xlate. So I want my TCL doing the reading/writing as efficient as possible.

My question is: Is it more efficient to use redirection, or to use the TCL file commands to do this?
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- January 4, 2006 at 3:48 am #58045
  
  Anonymous
  Participant
  
  Matt,
  
  How do you mean redirection?
  
  Greg
- January 4, 2006 at 2:01 pm #58046
  
  Anonymous
  Participant
  
  By using redirection, like:
  
  exec ls > jml.txt
  
  instead of tcl commands:
  
  set fileid [open jml.txt w]
  
  puts $fileid [exec ls]
  
  close $fileid
- January 4, 2006 at 5:27 pm #58047
  
  Anonymous
  Participant
  
  I’m open to correction on this point but I believe that when you exec TCL creates a subprocess to contain the running program. I assume this means a shell. The file command executes directly from TCL so it should be faster. If I have time I may test it…
  
  Cheers,
- January 9, 2006 at 2:57 am #58048
  
  Richard Hart
  Participant
  
  Matt.
  
  I would be very surprised so find an ‘exec’ running quicker than ‘in-line’ code as the exec has to perform similar file ops AND start its own process.
  
  If you are using files to read/write, be careful to ensure that a file is not being read at the same time it is written.
  
  We use one ‘file’ interface and we timestamp the output file to the nearest hour. The ‘read’ process runs an hour ‘behind’ to avoid conflict.
- January 9, 2006 at 1:03 pm #58049
  
  Anonymous
  Participant
  
  Your point is well taken. Thank you both very much.
- February 17, 2006 at 9:08 pm #58050
  
  Brad Dorr
  Participant
  
  Matt, in another discussion you mentioned that you have a WEB front end. I am in the processes of doing that. I have loaded Apache onto our Unix server. I have created some simple cgi scripts to run a hciconnstatus command return the results. I would like to be able to run a tcl script. You mentioned that you called the tcl script from the cgi script how can you send me an example?
- February 17, 2006 at 9:57 pm #58051
  
  Vamshi Mugu
  Participant
  
  Hi Matt and Brad,
  
  Please post the web stuff to the board. I am interested in it too.
  
  thanks,
  
  vamshi.
- February 21, 2006 at 7:14 pm #58052
  
  Tom Patton
  Participant
  
  I use the tcl file commands only because I want more control over how I open e.g. appends etc., and lock contention so I can handle the errors (if any).
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TCL Opinions wanted – file reading/writing

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