Technology Tales

Recalling previous commands in the Korn shell

18^th May 2007

The default shell on Solaris boxes seems to be Korn and the version that I have encountered doesn't appear to allow obvious access to the command history. In the bash shell, the up and down cursor keys scroll through your command history for you, but Korn doesn't seem to allow this. Thankfully, there is another way: you can set up the editor vi as the default method for gaining access to the command history by adding the following line to the .profile file in your home directory:

set -o vi

Then, you can use the Vi (it's pronounced vee-eye, apparently) commands ESC+h and ESC+j to move up and down the list of previous commands. That, or, assuming that you have access to it, just use the bash shell anyway...

Checking existence of files and directories on UNIX using shell scripting

23^rd April 2007

Having had a UNIX shell script attempt to copy a non-existent file, I decided to take another look for ways to test the existence of a file. For directory existence checking, I was testing for the return code from the cd command, and I suppose that the ls command might help for files. However, I did find a better way:

if [ -f $filename ]
then
    echo "This filename [$filename] exists"
elif [ -d $dirname ]
then
    echo "This dirname [$dirname] exists"
else
    echo "Neither [$dirname] or [$filename] exist"
fi

The -d and -f flags within the evaluation expressions test for the existence of directories and files, respectively. One gotcha is that those spaces within the brackets are important too, but it is a very way of doing what I wanted.

HTML Tidy for Windows

22^nd March 2007

Drupal has modules (Import HTML and its helper Static HTML together make up one option) for importing static (X)HTML pages into its database, and it needs HTML Tidy to work. Since I am playing with the thing on Windows, I went out and snagged the version for that OS. Being either lazy or bloody-minded, I tried an XHTML page with PHP code embedded in it and, needless to say, the thing choked. I must try it with plain XHTML instead.