Re: [MLUG] backup via cron

[Mike Miller <EMAIL:PROTECTED>]

On Sat, 4 Feb 2006, Stephen Montgomery-Smith wrote:

> I personally would call this "feature" of bash a bug.  It seems natural 
> to me that it should strip out the ^M's before passing it to growisofs.
>
> (On the other hand, I bet the other shells have this problem also.)


The problem is that it is possible to have a carriage return character in 
a filename!  That may be a strange choice, but it can be done, so the 
shell has to interpret the character literally or risk making a serious 
mistake.  This is me making a file called "crap^M" in bash, but note that 
the ^M is not visible (the command line wraps to the next line instead of 
showing the character):

# echo 'bob' > 'crap
'

# ls crap*
crap?

# cat 'crap
'
bob

# rm 'crap
'

So to do this I hit Ctrl-V Ctrl-J in succession.  The Ctrl-V tells the 
shell to interpret the next character literally.  The Ctrl-J produces a 
Ctrl-M (aka ^M) character, but I don't know why it works that way!  I 
found out because in tcsh, the Ctrl-M produces a ^J, which is visible in 
tcsh, and so I tried Ctrl-J and found that it produced the ^M.

So a file name can contain a control character in either bash or tcsh. 
This must occasionally cause some serious problems.

Mike

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