Although nearly all apps today are use some sort of
point-click, windowing front end, there are plenty of us who still use the
command-line when available. It's not
that we're set in our ways, it's that for many repetative tasks, the command-line
provides us with enough shortcuts that we're just way more efficient with a few
key strokes.
This brings me to Oracle's SQL*Plus, or more specifically,
running "sqlplus" from the command-line.
"sqlplus" has long provided the
ability to edit the previous command in it's buffer, either pulling it up into
an editor or using a few commands to change it in place (such as "
CHANGE//").
But obviously this is limited.
In comes "rlwrap". This application is also nothing new, but did
you know it's available from within Cygwin?
This issue came up during Tanel Poder's recent Training Day at Hotsos
Symposium 2010. He gave some great
examples of "rlwrap"'s power using it from Linux, then laid the
gauntlet down by saying it should
work under Cygwin, but he hasn't tried it and we should let him know if we can
get it working. That was enough for me!
I've used Cygwin for some time as a way to start an XWin
server, in support of other apps that require it (such as Oracle's installer).
I reviewed the my installation source (
x.cygwin.com)
and ran the installation again to see if "rlwrap" is available.
Sure enough, if you change the
View to
be by Category, then you'll file "rlwrap" under Utils:
In the screenshot above you can see "rlwrap" is
already installed, but this was taken from my current install, so you get the
idea.
The installation process dumps "rlwrap" under c:\cygwin\bin
by default. Now comes the power of the
tool!
From your PC, open a Cygwin XWin server to work off of, then
an xterm from this XWin server session.
From the xterm session you can fire off your "rlwrap"
commands. You can run them
from the XWin server session, but I prefer to instead use that as a central
session, firing off separate xterm sessions per connection I plan on making. In my $HOME directory I created a setup
script which defines a series of aliases, one per color-coded xterm screen:
alias black="xterm -fn '-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg black
-fg gainsboro &"
alias brown="xterm -fn '-adobe-courier-*-r-*-*-12-*-*-*-*-*-10'
-ls -geometry 140x35+50+20 -bg brown -fg gainsboro &"
alias blue="xterm -fn
'-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg
darkblue -fg gainsboro &"
alias darkred="xterm -fn '-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg darkred -fg gainsboro &"
alias green="xterm -fn
'-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg
green4 -fg gainsboro &"
alias purple="xterm -fn '-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg purple4 -fg gainsboro &"
alias teal="xterm -fn
'-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg
darkcyan -fg gainsboro &"
alias white="xterm -fn
'-adobe-courier-*-r-*-*-12-*-*-*-*-*-10' -ls -geometry 140x35+50+20 -bg white
-fg black &"
This way typing "blue", for example, quickly
gives me a new blue background, white foreground xterm.
Back to "rlwrap" power. A simple example of the command is as
follows:
rlwrap -r sqlplus dherri@ORCL1
Within this sqlplus session I now have full command-line
history using the arrow keys. Plus with
the "-r" argument, "rlwrap" will "remember", so
to speak, all text that passes on the screen.
What this means is through the TAB key you can now quickly access output
from previous queries. For example, suppose
you wanted to query an AWR view but couldn't remember the name. So you enter:
SELECT view_name
FROM dba_views
WHERE view_name LIKE 'DBA_HIST%'
ORDER BY 1;
Now the output list of view names is in rlwrap's buffer,
which means the view names are available for command completion. If you enter:
SELECT * FROM DBA_HIST_SQL
… and hit TAB twice, you'll get the following displayed:
DBA_HIST_SQLBIND DBA_HIST_SQLTEXT DBA_HIST_SQL_PLAN DBA_HIST_SQL_WORKAREA_HSTGRM
DBA_HIST_SQLSTAT DBA_HIST_SQL_BIND_METADATA DBA_HIST_SQL_SUMMARY
This is just a small sampling of what "rlwrap"
can provide in terms of added efficiency within sqlplus command-line or for
nearly any app for that matter (RMAN quickly comes to mind). The main point I'm raising here is Windows
users need not be excluded from the benefits of command-line completion using "rlwrap".
For more detail on "rlwrap" and excellent
examples of applying its use, see Tanel Poder's blog @
blog.tanelpoder.com or his new tech site @
tech.e2sn.com.
