从TCL调用python脚本并自动创建文件

Question

I wrote a python script that takes care of creating a file atomically as described in this other question . The file that gets created by the script is somewhat big (about ~1.5MB) as seen below:

$ ./my_script.py --output_file some_directory/my_file.txt
$ ls -l --block-size=K some_directory/my_file.txt
-rw------- 1 foouser foogroup 1477K Aug  7 17:39 some_directory/my_file.txt

Unfortunately, due to some legacy infrastructure and the way things are set up, this script needs to be called from within a TCL script. Here is the way in which I am currently doing that:

#!/usr/bin/env tclsh
set PY_SCRIPT my_script.py
puts [exec $PY_SCRIPT --output some_directory/my_file.txt]

The problem that I am seeing is that the generated file does not seem to be created atomically anymore (atomicity is a requirement for my application). The TCL puts command documentation says the following:

Tcl buffers output internally, so characters written with puts may not appear immediately on the output file or device; Tcl will normally delay output until the buffer is full or the channel is closed.

I believe this explains why my file is not being atomically created anymore. I'm not an expert in TCL, so I am not sure how to accomplish atomic file creation in the TCL script.

Any suggestions?

Answer 1

我认为您想要的只是flush stdout 。

Answer 2

A direct translation of the Python code that you link to would be something like this (untested code):

package require Tclx

set f [open $tmpFile w]
puts -nonewline $f $text
sync $f    ; # flush is performed implicitly
close $f

file rename -force $tmpFile $myFile

The TclX package is needed to get the sync command. (This will probably not work on Windows.)