23.7 Safer File Deletion in Some Directories

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
 
./-
 

% 

touch ./-i

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:

~
 

% 

cd


% 

touch ./-i


% 

cd



 somedir


% 

ln ~/-i .


   ...

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  ]