emptying a file and keeping its ownership
Jonathan I. Kamens
jik at athena.mit.edu
Tue Jan 1 08:40:30 AEST 1991
Several people have suggested using
> $FILE
to truncate a file while retaining its old permissions. This will work under
sh or ksh or bash or other shells that allow null commands for redirection.
Unfortunately, csh and tcsh do not allow such null commands :-(. Therefore,
I'd like to point out another way to do this that works on most platforms I've
seen.
From the man page for cp(1):
DESCRIPTION
File1 is copied onto file2. By default, the mode and owner
of file2 are preserved if it already existed; otherwise the
mode of the source file modified by the current umask(2) is
used.
Therefore, you can use
cp /dev/null $FILE
to truncate a file and save its current permissions.
I hope this helps.
--
Jonathan Kamens USnail:
MIT Project Athena 11 Ashford Terrace
jik at Athena.MIT.EDU Allston, MA 02134
Office: 617-253-8085 Home: 617-782-0710
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