lock file while Add-Content

Ok, I have one PS1 file with about 170 lines like this:

$body = "something"
Add-Content "$path$filename" $body
$body = "something"
Add-Content "$path$filename" $body
....

it takes about 1 or 2 sec to complete whole operation. But, during this
operation, "$path$filename" filename is open for edit by other process, and
that’s the problem. Sometimes, somebody just delete the file in the middle of
the Add-Content process.

I want to "lock" (or something like that) file until PS1 script finish his
job.

tnx

You can accumulate the content into a variable and then write it to the file.

$body += "something"
Add-Content "$path$filename" $body


If its a large content it is better to use the StringBuilder:

$body = new-object System.Text.StringBuilder
[void]$body.Append("text")

(...)

Add-Content "$path$filename" $body


-----
Shay Levi
$cript Fanatic
http://scriptolog.blogspot.com
Hebrew weblog: http://blogs.microsoft.co.il/blogs/scriptfanatic

Tnx, but it isn’t perfect solution. I can group 170 Add-Content into 3 large
Add-Content commands (using $body += accumulation), but file is still
vulnerable to edit/delete during that (now shorter) time.

There is only one perfect solution – lock file until last Add-Content.

help


"Shay Levi" wrote:

You can write your content to a temporary file in a safe place and when you
finish switch the files.
Why would someone delete the file? One can delete the file even if you'll
successfully update its content regardless
of the method used to update it.

-----
Shay Levi
$cript Fanatic
http://scriptolog.blogspot.com
Hebrew weblog: http://blogs.microsoft.co.il/blogs/scriptfanatic

Ok, I’ll be more detailed.

Nobody edit/delete file in the middle of creation process. The thing is that
my PS1 script export data from the SQL server into text files on remote
shared folder. But, that folder is monitored every 10 seconds by one EXE
program, and he import that text files in the other SQL server database.

Problem is: every 10 seconds EXE program imports every single txt file,
including the one in the middle of the creation! That leads to bad import
data. To make things even worse, EXE take that “half� file and import it,
next PS1 add-content create ANOTHER file with SAME filename and put next half
of content, and in a 10 seconds EXE will terminate himself with error: There
can’t be 2 files with same filename (unique column in database).

Your suggestion to make file in temp folder + move item is bypass of the
problem, but it creates unnecessary overhead and HDD disk operations. System
(PS1 script) must be very, very fast, it creates several hundreds files per
second.
Lock file in the creation process is great solution, but how?


Sorry for my bad English.


"Shay Levi" wrote:

No, your best solution is likely not to use a lock. The lock itself may
cause the other process to crash.

The best solution would be to first generate the entire body, then write it
to file all at once to avoid any blocking.

Set-Content $path $entirebody

However, if you do insist that you want to use a locked file, and if that
lock will not cause the other process to crash, then it is possible to
create the file with an initial lock.

# Create the file, it is also locked.
$fs = [IO.File]::Create($filename)
# Make a StreamWriter for ease of access
$sw = New-Object IO.StreamWriter($fs)
# Write some text to it
$sw.WriteLine("some text")
$sw.WriteLine("some more text")
# Close the file, don't forget this or it will remain locked
$sw.Close()

"MiroslavK" <MiroslavK@xxxxxx> wrote in message
news:56D84B88-2C6E-4BD2-BFC1-AD2A149B8BE4@xxxxxx

tnx, tnx a lot !!!

"Steven Hystad" wrote: