UNIX for Advanced & Expert Users

I now have a theory regarding the three behaviors that Charles reported. The ability to source a function was intended to be used with ksh style functions. These normally create their own scope and by sourcing them they behave like like posix style function.

Charles is defining a posix style function and then is sourcing that. This was not intended to happen. My theory is that AIX is advanced enough to support an early implementation of the function sourcing code. And in this implementation the attempt to source a posix style function is simply ignored.

And my theory continues that users were surprised that some functions could be sourced while other could not. And so, in the spirit of least surprise, ksh was modified to tolerate the sourcing of posix style functions.

The documenation does say that sourcing ksh style function is the feature that was added to ksh. The docs neither allow or prohibit sourcing a posix style function as far as I can see. Whether or not my theory is correct, sourcing a posix style function is an undocumented feature and Charles clearly has seen two different behaviors. I think it would be wise to stick only to the functionality that is explicitly allowed by the documentation.

Note - some versions of Linux had/have /usr/dash which is then symlinked to via /bin/ksh.
dash is NOT ksh. Do you have ksh88 or ksh93 on AIX? ksh88 is what you get as ksh on Solaris 9, 10, 11, by default. FWIW. I cannot be sure at all. But your Linux version appears not to be ksh93. dash was an early thing for Linux to get past the fact that ksh93 was not open source. Cygwin still has it in place of ksh.

Please post the output of (on Linux only):

Code:

ls -l /bin/ksh 
strings /bin/ksh | grep -i version

I don't know enough about AIX to comment on Perderabo's idea - it appears to have merit. IBM tends to be like Apple: everything on the command line has to do be redone/recoded/re-engineered, and then made to comply with POSIX later on.

PS: posting your flavor of Linux might have helped earlier on. Otherwise this was a very good question. Thanks.

"ksh" in AIX is a ksh88 which is unchanged since i work with AIX (v 3.2.3, ~1992), which is pretty long. To get a ksh93 you have to call "ksh93" explicitly.


One question i have for charles, though: why is it necessary to source anything? Why don't you use the "FPATH" variable and put your functions into a common path, similarly to a shared library?

FPATH works like the PATH, but for KornShell functions. put all your functions into separate files named the same as the function: if FPATH is set to "/foo/bar" the file "/foo/bar/boom" will contain the sole function "boom()". I use this for all my scripts in conjunction with a variable "DEVELOP", which switches between a copy of the library in my HOME and the common library. This way i can modify the lib functions without interrupting the production code:

Code:

#! /usr/bin/ksh

if [ -z "$DEVELOP" ] ; then
     . /usr/local/lib/ksh/StdEnv
else
     . ~/lib/StdEnv
fi

.... rest of the script

file /usr/local/lib/ksh/StdEnv contains:

Code:

if [ -z $DEVELOP ] ; then
     FPATH=/usr/local/lib/ksh
else
     FPATH=~/lib/ksh
fi

FOO=bar
...            # and all sorts of other environment settings

In my personal profile "$DEVELOP" is set so that scripts called with my user always use the local copy of the lib (or i unset it to use the common copy), all scripts started with non-personal users have "$DEVELOP" not set and therefore use the common library.

I hope this helps.

bakunin