[Linux-disciples] Easy Question - Changing Permissions a list of files

[Stephen R Laniel]

On Mon, Nov 14, 2005 at 09:50:46AM -0500, Jason Smith wrote:
> Well, for example, I didn't know you could use "*" with chmod. I am  
> not sure what you call things like "*". I know in Westlaw for example  
> we use "!", "*", and "%"... I am at a complete loss for vocabulary  
> this morning...

What you want to call that is a 'wildcard' -- a string that
stands for another string. In particular, 'a*b' is a 'shell
wildcard'. You're likely to see two kinds of wildcards:
shell wildcards and regular expressions. Regular expressions
can be exceedingly complicated little beasties, like
(Perl-style)

(\w+)\W\1

which says "a sequence of one or more word characters
[meaning letters and underscores, I believe], followed by a
non-word character [like a space], followed by the sequence
of word characters that we started with." Which is a precise
way of saying "a repeated word." That string would match
"that that" or "and and", for instance.

The trick with Adam's example -- the "chmod [stuff] *" thing
-- is that the shell expands '*' before 'chmod' sees it. So
if you have three files -- 'a', 'b', and 'c' -- that command
expands to

chmod [stuff] a b c

which then gets handded off to the chmod command.
Anytime you're in the shell you can use '*'.

-- 
Stephen R. Laniel
steve at laniels.org
+(617) 308-5571
http://laniels.org/
PGP key: http://laniels.org/slaniel.key
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