Korn Help

Question

Hi, I'm new to Unix and trying to learn how to use the Korn Shell. If anyone can help me with setting this up it would be greatly appreciated.
So far I have set up OS X's terminal to default to ksh when starting up, and now I am trying to figure out how to set up my .profile . If I manually create a .profile in my home directory and put an alias in (alias a = ls -ltr) it doesn't recognize it at all. I'm not sure if it is different in OS X than in other unix implementations, but I'm having no luck.
Thank you for your time.

Answer 1

Nothing says you can't write ksh scripts, but use bash as your command line interface.
While I was writing ksh scripts, I was actually using tcsh as my command line shell. At the time, I felt tcsh had a friendlier user interface (for me). But in 2005, I switch to bash, as I could get the friendly command line interface and have all the scripting features I like in the ksh environment.
NOTE: Friendly is a relative term. To me tcsh and bash were friendlier, but you must keep in mind that I started with punch paper tape and 80 column punched cards as my original command interface. I spent years using the original Bourne shell which is extremely limited and not at all what is called a Bourne shell these days So your friendlyness mileage may vary.
But if you are going to stay with ksh, then you also need to know about .kshrc files. Generally when you login, your .profile will run, but if you drop into a sub-shell, then ONLY the environment variables will pass to the sub-shell. If you want those aliases in the sub-shell, you want to have them defined in a .kshrc file.
Some utilities allow you to drop into a sub-shell, for example gdb, vi/Vim, emacs, etc... I've also used software development environment where to enter a View, or Sandbox and this environment drops you into a sub-shell where you are allowed to check-out, modify, check-in, and submit file changes.
So put your export environment variables in your .profile and your aliases, PS1 command prompt, function() declarations in .kshrc
And speaking of function() declarations, an alias is fine for simple commands, but sometimes you want something more complex that maintains shell context, and for that you use functions()s.
fred()
...do something more complex that might set...
...shell local or environment variables the continue...
...to exist after returning from the function...
...or issue a "cd" command to change your current...
...working directory...
Now you would just invoke this function by specifying it name: fred as a command.
Things I put in a function. My vi command remembers the last file I edited, so if I use the vi command without arguments, it just uses the saved file name from the previous invocation. I save the previous command line arguments in a shell local variable.
I have a function that does simple math, and the answer is saved in a local variable. I can then invoke my math function and reference the previous answer without needing to manually type it in or do a copy and paste.
I have my own rather complex "cd" command that is implemented as a function. It has its own memory. Kind of like pushd and popd only implemented the way I like.
ksh function() can be very useful.