Re: !!:$

[Peter Stephenson <pws@csr.com>]

keef wrote:
> yarr mateys!

Er, yeah.

> consider the following:
> 
> % touch somefile
> % chmod 755 !!:$
> 
>  -this essentially will chmod 755 the last arg in the previous history cmd
> 
> now then, id like to incorporate this into my .zshrc
> 
> something to the effect of:
> alias ch="chmod 755 !!:$"

Try:

  alias ch='chmod 755 $_'

It works in this case, but you can't get the full effect of history
expansion in an alias since they are expanded too late.

The zsh/parameter module does have $history and $historywords to help
access the history, but unfortunately the interface isn't very easy to
use in a case like this.  $history is an associative array and you need
to know the event number, which currently isn't available as a
parameter: you can get it from a prompt, but not directly.  This strikes
me as a curious omission.  How about adding it using the same name as
bash?  Then you can always get the full previous line as
$history[$((HISTCMD-1))].  Hence you can do lots of tricks.  The
equivalent of the above would be:

ch() {
   # Don't want ksh_arrays, ...
   emulate -L zsh

   # Make sure the parameter module is loaded
   zmodload -i zsh/parameter

   local prev
   # Split the previous line using normal shell word splitting.
   prev=(${(z)history[$((HISTCMD-1))]})
   # Retrieve the final element of the line.
   chmod 755 $prev[-1]
}

Index: Doc/Zsh/params.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/params.yo,v
retrieving revision 1.23
diff -u -r1.23 params.yo
--- Doc/Zsh/params.yo	8 Oct 2004 14:37:24 -0000	1.23
+++ Doc/Zsh/params.yo	16 Nov 2004 14:17:28 -0000
@@ -535,6 +535,12 @@
 command under a different
 group ID by `tt(LPAR()GID=)var(gid)tt(; command+RPAR())'
 )
+vindex(HISTCMD)
+item(tt(HISTCMD))(
+The current history line number in an interactive shell, in other
+words the line number for the command that caused tt($HISTCMD)
+to be read.
+)
 vindex(HOST)
 item(tt(HOST))(
 The current hostname.
Index: Doc/Zsh/zle.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/zle.yo,v
retrieving revision 1.44
diff -u -r1.44 zle.yo
--- Doc/Zsh/zle.yo	22 Sep 2004 04:37:02 -0000	1.44
+++ Doc/Zsh/zle.yo	16 Nov 2004 14:17:29 -0000
@@ -645,7 +645,10 @@
 The current history number.  Setting this has the same effect as
 moving up or down in the history to the corresponding history line.
 An attempt to set it is ignored if the line is not stored in the
-history.
+history.  Note this is not the same as the parameter tt(HISTCMD),
+which always give the number of the history line being added to the main
+shell's history.  tt(HISTNO) refers to the line being retrieved within
+zle.
 )
 vindex(KEYMAP)
 item(tt(KEYMAP) (scalar))(
Index: Src/params.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/params.c,v
retrieving revision 1.92
diff -u -r1.92 params.c
--- Src/params.c	1 Oct 2004 19:48:57 -0000	1.92
+++ Src/params.c	16 Nov 2004 14:17:30 -0000
@@ -184,6 +184,7 @@
 IPDEF4("!", &lastpid),
 IPDEF4("$", &mypid),
 IPDEF4("?", &lastval),
+IPDEF4("HISTCMD", &curhist),
 IPDEF4("LINENO", &lineno),
 IPDEF4("PPID", &ppid),
 

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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