[calpaterson]

In many (all?) unix shells, globs are expanded by the shell before being passed to the program.

   'ls *.jpg' 

is passed expanded to 'ls 1.jpg 2.jpg 3.jpg' BEFORE ls is run. This choice means that if a program wants to use another style of regular expression (ie: pcre), it must be enclosed in quotes on the shell, ie:

  "ls | grep -P '.*jpg'"

[ralph]

Yes, that's globbing, but I was wondering what the OP meant by argument expansion. It could be just globbing, or include globbing but extend to variable expansion, braces, command substitution... It's hard to put a case that having the shell do these things is the right way to do it without understanding the OP's point clearly.

[tedunangst]

Minor point: if the glob doesn't match it isn't expanded. Sometimes useful. I rarely escape scp commands for instance.

[ralph]

See `failglob' elsewhere on this page. What you suggest is sometimes useful but also sometimes wrong and hard to spot because the glob might match locally and one not realise.