06-17-2012
Hi, Scrutinizer.
Quote:
Originally Posted by
Scrutinizer
It seems to me any solution should always make use a temporary intermediate file for safety reasons. If we read the whole file into memory and then write it back to the same file, we run the risk of losing the original in case of power failure during the write-back phase..
With a temporary file there is only mv involved, which is only a rename if the temporary file is in the same dir on the same file system, so a temporary file in the same directory instead of /tmp for example may be preferably. If we use /tmp for example for the intermediate file, a temporary rename to .bak of the original until the move from /tmp may be required and safest will probably be to keep the .bak until the user deletes it..
When was the last time you know that that happened to
anyone? Most important *nix boxes will be backed up with a UPS. I think it is
far more likely to fall prey to plain old
user error.
However, I sometimes allow myself the luxury of following:
Quote:
"Unix was not designed to stop its users from doing stupid things, as that would also stop them from doing clever things." - Doug Gwyn
--
Unix philosophy - Wikipedia, the free encyclopedia
Best wishes ... cheers, drl
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TEMPNAM(3) 1 TEMPNAM(3)
tempnam - Create file with unique file name
SYNOPSIS
string tempnam (string $dir, string $prefix)
DESCRIPTION
Creates a file with a unique filename, with access permission set to 0600, in the specified directory. If the directory does not exist or
is not writable, tempnam(3) may generate a file in the system's temporary directory, and return the full path to that file, including its
name.
PARAMETERS
o $dir
- The directory where the temporary filename will be created.
o $prefix
- The prefix of the generated temporary filename.
Note
Windows uses only the first three characters of prefix.
RETURN VALUES
Returns the new temporary filename (with path), or FALSE on failure.
CHANGELOG
+--------+---------------------------------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+---------------------------------------------------+
| 4.0.3 | |
| | |
| | This function's behavior changed in 4.0.3. The |
| | temporary file is also created to avoid a race |
| | condition where the file might appear in the |
| | filesystem between the time the string was gener- |
| | ated and before the script gets around to creat- |
| | ing the file. Note, that you need to remove the |
| | file in case you need it no more, it is not done |
| | automatically. |
| | |
+--------+---------------------------------------------------+
EXAMPLES
Example #1
tempnam(3) example
<?php
$tmpfname = tempnam("/tmp", "FOO");
$handle = fopen($tmpfname, "w");
fwrite($handle, "writing to tempfile");
fclose($handle);
// do here something
unlink($tmpfname);
?>
NOTES
Note
If PHP cannot create a file in the specified $dir parameter, it falls back on the system default. On NTFS this also happens if the
specified $dir contains more than 65534 files.
SEE ALSO
tmpfile(3), sys_get_temp_dir(3), unlink(3).
PHP Documentation Group TEMPNAM(3)