Using noclobber (13.6) and read-only files only protects you from a few occasional mistakes. A potentially catastrophic error is typing:
%rm * .o
instead of:
%rm *.o
In the blink of an eye, all of your files would be gone. A simple, yet effective, preventive measure is to create a file called -i in the particular directory in which you want extra protection:
touch ./- |
% |
---|
In the above case, the
*
is expanded to match all of the filenames in the directory.
Because the file
-i
is
alphabetically listed (51.3)
before any file except those that start with
one of these characters:
!#$%&`()*+,
,
the
rm
command sees the
-i
file as a command-line argument.
When
rm
is executed with its
-i option (21.11),
files will not be deleted unless you verify the action.
This still isn't perfect. If you have a file that starts with a comma
(,
)
in the directory, it will come before the file starting with a dash,
and
rm
will not get the
-i
argument first.
The -i file also won't save you from errors like:
%rm [a-z]* .o
[Two comments about Bruce's classic and handy tip: first, if lots of users each make a -i file in each of their zillions of subdirectories, that could waste a lot of disk inodes (1.22). It might be better to make one -i file in your home directory and hard link (24.4) the rest to it, like:
~ | % |
---|
Second, to save disk blocks, make sure the -i file is zero-length - use the touch command, not vi or some other command that puts characters in the file. -JP ]
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