Tcl open command

[Mark Perschbacher]

I am playing around with a proc, trying to get it to append some data to the beginning of an existing file.  With the value of “a” or “a+”  for the access argument, I can get it to append at the end of the file.  Does anyone know of a way to append the data to the beginning?

Topic

[Rob Abbott]

You can use seek to get the pointer to the beginning of the file.  But I think any data written will over-write existing data, not prepend.

You might try something like this:

Code:

set new_data “this is new data, which should be prepended”
set filename foo.txt
set existing_data [read_file $filename]
write_file $filename ${new_data}${existing_data}

Rob Abbott
Cloverleaf Emeritus

[Mark Perschbacher]

Rob, that did the trick.  I seriously don’t know what I would do without the huge braintrust that is Clovertech, thanks

[Max Drown (Infor)]

I totally cheat when I need to do this. Instead of using the tcl file functions, I use cat, perl, whatever system commands I need.

Example:

Code:

exec echo “foobar” >> /path/file.txt

-- Max Drown (Infor)

[Mark Perschbacher]

We run Clovleaf in a Windows environment.  When I run that command at the tcl prompt, I get a “couldn’t execute echo, no such file or directory error.

[Max Drown (Infor)]

You’d have to have the unix utilities installed.

-- Max Drown (Infor)

[Author]

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