Re^6: Writing to a file atomically without renaming


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Re^6: Writing to a file atomically without renaming

by waswas-fng (Curate)

on Jun 30, 2005 at 23:22 UTC ( [id://471509]=note: print w/replies, xml )

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in reply to Re^5: Writing to a file atomically without renaming
in thread Writing to a file atomically without renaming

backup_file has different perms because you copied the file to a new file as a different user. I am not saying backup_file is gone if you hit that case -- only that you end up in a situation where your app or the other apps that use that file are looking at corrupt data (they don't know about backup_file). cat backup_file > file does the following:

trunc file.

# this is where you have the race condition.

redirects the data in backup_file to file.  
closes file
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-Waswas

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Re^7: Writing to a file atomically without renaming
by Transient (Hermit) on Jul 01, 2005 at 02:45 UTC

here

Worst case scenario the cat of the backup_file to temp_file fails and you're left with a corrupt "file" and the extra "backup_file" which would have to be moved back manually.

Fin

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