Re: shell script replacing original file

On 2008-03-28, Maxwell Lol wrote:
"Ming Ching TIew" <nospam@xxxxxxxxxx> writes:

I want to know if it is 100 % safe to do this :-

$ cat myfile | sed -e '...........' > myfile

(p.s. No need for cat.)

In this case, cat is needed so that myfile is opened before the
redirection truncates it. Even so, I wouldn't trust it.

Well, if you want to be 100% safe, perhaps something like this is better

sed -e '...........' <myfile > myfile.new
mv myfile myfile.old && mv myfile.new myfile && /bin/rm myfile.old

If it's a large file, and the disk fills up, it won't delete the
original file. (untested)



--
Chris F.A. Johnson, author <http://cfaj.freeshell.org/shell/>
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence
.

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