I am trying to understand a shell script and
am unable to figure out what this code snippet implies:

$(set *; echo ${*/#/-a })

This is part of this line of code:
mutt ${EMAILGROUP} $(set *; echo ${*/#/-a }) -s "EMAILSUBJECT"

mutt is an email client. '-a' is the token for email attachment.

Any help is appreciated.

Thanks,
MD

I didn't know either, I'm going to venture a guess that # is the number of files. So, maybe the echo ${whatnot} is piping the attachments.

This is the sort of thing that really makes me nuts about shell-scripting, the ambiguity between commands, $PATH programs and builtins.

Actually
is shell parameter expansion of the form
It takes each positional parameter (a.k.a. arguments) and add -a followed by a blank space at the beginning. The special character # used as pattern is an anchor. It means "at the beginning" and if used alone it is meant to mark the position before the first character so that you can simply add something there, leaving the rest untouched.

As you guessed, it is a way to add all the files in the current working directory as attachments, by preceding each name with the -a option of mutt. The set command sets positional parameters (arguments) of the current shell in order to use them as $* in the parameter substitution.

Some references:
http://www.gnu.org/software/bash/man...nal-Parameters
http://www.gnu.org/software/bash/man...eter-Expansion
http://www.gnu.org/software/bash/man...name-Expansion
http://www.gnu.org/software/bash/man...he-Set-Builtin

Please note that the asterisk * has a different meaning in the set statement above and in parameters expansion. The former is the wildcard for filename expansion, the latter is the special shell variable $* to which all the positional parameters are assigned.

I'm not 100% sure, because I don't have that installed, but this is what I gather:

mutt <destinationBox??>, all the files in the current directory beginning with a number, "-a" to signal attachments, "-s" says we have subject of "this is my subject"

Oops, he beat me while I was typing that up. And I totally mucked up the anchor..