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Final round of computer tweaks

After spending a substantial amount of time tweaking my system, it now works as well as I want it to, and I am hereby making a public promise not to touch my config files for a month.  I want to be able to post a screenshot a month from now with a "last modified" timestamp corresponding to today.  (The only exception is M-x / smex stuff in .emacs; if the author of the package fixes the broken fuzzy matching, I'll add it in.  No other changes are allowed, though!)

So what went into the final round of updates?..

First, there were more tweaks to .bashrc and .inputrc.  I turned on bash completion; here are some notes about this:

bash_completion is very handy, but has a few annoyances.  First, the bash startup time increased to 2+ seconds.  This was fixed by calling the completion functions dynamically -- solution was found on http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=467231; dyncomp.sh script I saved locally.

To prevent cd/find from completing random useless things, put complete -d cd find in .bashrc

To prevent tilde from getting expanded: edit /etc/bash_completion; look for function named _expand(); comment out all code (but leave one dummy line e.g. foo=bar, o/w bash complains). If used dynamic completion replacement above, look for the function _expand as a sep. file in bash_completion.d

For .inputrc I added several customizations -- set show-all-if-ambiguous on, history-search-{forward/backward}, etc. These things are handy; you might want to google for them if you don't already use them. I realized a short time later that any keybindings involving meta (e.g. "\M-o") failed to work in bash shell on Dreamhost.  The problem is a buggy version of readline that breaks in unicode locale and the solution is to replace "\M-" with "\e" (e.g. "\eo").

Ok, now let's get to the good stuff!  Here it is: any time I work in a terminal, I can open Windows Explorer in the current directory, or in any directory I specify.  I aliased this to a single key 'e'.  It's handy!  Conversely, if I am browsing a directory in Explorer, I can launch a terminal window in that directory using a single shortcut key (e.g. Win-T).  And finally, if I am in Emacs, I can launch either Windows Explorer or the terminal in the directory of the current buffer (or current dired buffer) with Win-E and Win-T respectively.  How does this magic work?

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#!/usr/bin/bash
# Open explorer in the current directory or directory of the argument
#
# Unix/Windows path conversion: -- could've done it w/ cygpath in hindsight
# pwdWin=`pwd|perl -p -e 's/\/cygdrive\/(.)/\1:/; s/\//\\/g'`
# note that you have to double-escape special characters here
 
cygwin_root=/cygdrive/c/cygwin
 
if [ $# -eq 0 ]; then
    absPath="$(pwd -P)"
else
    absPath="$(realpath "$1")"
fi
 
# the following will always execute unless the path is printed as c:/...
# in which case we can proceed directly to replacement
if [ "${absPath:0:1}" = "/" ]; then # either have /cygrive/c/..., or:
	# special case: starts with /, e.g. / or /usr
    base_dir=$(echo $absPath | awk -F/ '{print $2}')
    # when absPath=="/", so basedir=="":
    if [ "$base_dir" = "" ] || [ "$base_dir" != "cygdrive" ]; then
	absPath=$cygwin_root$absPath
    fi
fi
winPath=$(echo $absPath|perl -p -e 's/\/cygdrive\/(.)/\1:/; s/\//\\/g')
explorer /e, "$winPath"

There are extra checks necessitated by idiosyncrasies of Cygwin paths. Ok, so this is standard bash scripting; no biggie. Now, how do we call terminal from Windows?.. This piece of magic requires several components.
The first is writing a program to launch the terminal (mrxvt in my case) in a particular directory. There are two ways to do this: VB script or a batch file. VB script is a more modern solution, and could look like this:

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Set WshShell = WScript.CreateObject("WScript.Shell")
WshShell.CurrentDirectory = "C:\home\Leo"
Set wshSystemEnv = wshShell.Environment( "PROCESS" )
wshSystemEnv( "DISPLAY" ) = "127.0.0.1:0.0"
'WScript.Echo "SYSTEM:  DISPLAY=" & wshSystemEnv( "DISPLAY" )
 
Dim StartInDir
If WScript.Arguments.Count > 0 Then
    StartInDir = CStr(WScript.Arguments.Item(0))
    Dim BashExeString
    BashExeString = chr(34) & "cd " & chr(34) & StartInDir & chr(34) & "; exec bash" & chr(34)
    Dim RunString
    RunString = "c:\cygwin\bin\run -p /usr/X11R6/bin /usr/local/bin/mrxvt -e /bin/bash --login -i -c " & BashExeString
    WshShell.Run RunString,0,false
Else
    WshShell.Run  "c:\cygwin\bin\run -p /usr/X11R6/bin /usr/local/bin/mrxvt -e /bin/bash --login -i",0,false
End If

The key aspect that makes this work is the execution of -c "cd [DIRECTORY]; exec bash;" command at the end of the chain run--mrxvt--bash. Run command, if you are curious, allows to launch commands that would otherwise spawn a terminal window. Exec bash is needed because otherwise bash exists after executing the -c string command.

Another way to write this is with a batch file:

@echo off
SET DISPLAY=127.0.0.1:0.0
SET CYGWIN_ROOT=\cygwin
SET RUN=%CYGWIN_ROOT%\bin\run -p /usr/X11R6/bin
SET PATH=%CYGWIN_ROOT%\bin;%CYGWIN_ROOT%\local\bin;%CYGWIN_ROOT%\usr\X11R6\bin;%PATH%
SET XAPPLRESDIR=/usr/X11R6/lib/X11/app-defaults
SET XCMSDB=/usr/X11R6/lib/X11/Xcms.txt
SET XKEYSYMDB=/usr/X11R6/lib/X11/XKeysymDB
SET XNLSPATH=/usr/X11R6/lib/X11/locale
cd c:\home\leo\
%RUN%  /usr/local/bin/mrxvt -e /bin/bash --login -i -c "cd "%1"; exec bash"

It turns out that the batch file runs noticeably faster on my computer.

There is an alternative approach to specify the terminal's start directory, in addition to the bash -c [string] command line option. You can set an environment variable and have .bashrc check for its existence and cd accordingly. This has the advantage of being a tiny bit faster than the preceding approach, but because all environment variables get cached, subsequent tabs of the terminal (mrxvt) will open in the directory in which the first tab started, which might not be the desirable behavior.

To get this working, put set STARTINGDIRECTORY=%1 into the batch file, use the run command
%RUN% /usr/local/bin/mrxvt -e /bin/bash --login -i, and put into .bashrc:

if [ ! -z "${STARTINGDIRECTORY}" ]; then # must strip literal quotation marks if any
    if [ "${STARTINGDIRECTORY:0:1}" = "\"" ]; then
	STARTINGDIRECTORY=$(echo "$STARTINGDIRECTORY"|sed 's/..* ./\1/')
    fi
    echo "starting in ${STARTINGDIRECTORY}"    
    cd "${STARTINGDIRECTORY}"
    unset STARTINGDIRECTORY
fi

Now the fun part: how do we invoke this for a particular directory as we browse it in Explorer?.. Autohotkey comes to our rescue! I found a piece of code on Stack Overflow to launch the windows command shell and tweaked it a little:

; Opens the command shell 'cmd' in the directory browsed in Explorer.
; Note: expecting to be run when the active window is Explorer.
;
OpenCmdInCurrent()
{
    WinGetText, full_path, A  ; This is required to get the full path of the file from the address bar

    ; Split on newline (`n)
    StringSplit, word_array, full_path, `n
    full_path = %word_array1%   ; Take the first element from the array

    ; Just in case - remove all carriage returns (`r)
    StringReplace, full_path, full_path, `r, , all  

    IfInString full_path, \
    {
        Run, c:\home\Leo\bin\mrxvt_win.bat "%full_path%"
    }
    else
    {
        Run, c:\home\Leo\bin\mrxvt_win.bat
    }
}

; ==== Win+T default ====

#t::
  Run, c:\home\Leo\bin\mrxvt_win.bat
Return

Notice how this hotkey is global -- if we are in Explorer, it will give us a terminal started in the directory being browsed. Otherwise, it will just launch a terminal. But what about Emacs?.. We'll do something sneaky: we'll tell Autohotkey to send Emacs a different key combo for Win-T and use a different set of bindings in Emacs:

#IfWinActive ahk_class Emacs
#e::^f3 ;for explorer
#t::^f4 ;for terminal
#IfWinActive

And in Emacs, we write the following piece of lisp code:

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(defun terminal-here ()   
  "Launch external terminal in the current buffer's directory or current dired
directory.  (Works by grabbing the directory name and passing as an argument to
a batch file.  Note the (toggle-read-only) workaround; the command will not run
in dired mode without it."
  (interactive)
  (let ((dir "") (diredp nil))
    (cond
     ((and (local-variable-p 'dired-directory) dired-directory)
      (setq dir dired-directory)
      (setq diredp t)
      (toggle-read-only)
)
     ((stringp (buffer-file-name))
      (setq dir (file-name-directory (buffer-file-name))))
      )
    (shell-command (concat "~/bin/mrxvt_win.bat \""dir"\" 2>/dev/null &") 
 (universal-argument))
    (if diredp (toggle-read-only))
))

(and there's a similar function to launch Windows Explorer). Bind them to C-F3 and C-F4 (in reality Win-E and Win-T translated by Autohotkey) and we are all done, 5 scripting languages later! Who said administering a Windows box isn't fun :)

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