[ILUG] Shell expansion questions

[Aidan Kehoe]

 Ar an 22u la de mi 10, scriobh Rory Winston :

 > I was just wondering if the following is possible in the shell.. I find the
 > $_ variable very handy (gives you the last argument of the previous
 > command), so you can type stuff like:
 > 
 > $ vim foobar.c
 > $ cat $_
 > $ gcc $_
 > 
 > Is there any way to get any other part of the previous command string? I.e.
 > if I type 
 > 
 > $/usr/bin/foobar foo.c
 > 
 > Can I repeat the command, say like:
 > 
 > $$__ bar.c

Yup. 

In zsh; in recent bash too; originally from the csh;  

!*	# The previous command; note no $
!!:0	# The first word of the previous command; /usr/bin/foobar just above. 
!!:1	# Second word; foo.c above. 
... and so on. Look up history substitution in your manual. 

 > 
 > And $__ (or similar) is expanded into the previous command
 > (/usr/bin/foobar)? Or are there any substitution mechanisms whereby I can
 > type something like 
 > 
 > $ s/foo.c/bar.c

Hmm. Not that I can think of, but "echo !! | sed 's/foo.c/bar.c/g'"
would do it. Mightn't be sufficiently shellish for you. 

 > and the previous command is re-executed with the substitution in place. If
 > anybody knows of any trickery to do this stuff (or similar tricks) it would
 > be very handy. If we have any users who prefer Korn to Bash, any ideas on
 > the same mechanisms in ksh?

-- 
`... when the elephant man broke strong men's necks, when he'd had too 
many Powers, ...'