korn tips - some useful korn shell techniques
Archive - Originally posted on "The Horse's Mouth" - 2007-09-25 12:09:32 - Graham Ellis1. If you set PS1 to a string that contains a "!" character, then you'll get the current history number reported as part of the prompt. If you want to rerun the same command number 246 later, all you then need to do is type
r 246
2. If you're debugging a Korn shell script and want to work out what it's doing in part of the script, add in
set -x
at the top of the section that you're especially interetsted in, and
set +x
at the end of that section. Then your script will give you a log of the lines as it runs them together with an indication of how the shell has expanded your shell variables and manipulated your other metacharactes
3. The Korn shell
whence -v
command will show you where the korn shell gets programs and instructions its to ru; unline the operating system's
where
command, whence will be able to tell you about functions, aliases, and builtins as well as the operating systems's stand alone programs
4. Global variables. In the korn shell, variables in the main code are, be dafualt, shared with variables of the same name within the functions. If you want a local variable in a function, you can create it with a
typedef var
command. We have an example of a shell script that defines a function and uses both a global and a local korn shell variable here