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Full Discussion: Emulate ksh's FPATH variable in bash
Top Forums Shell Programming and Scripting Emulate ksh's FPATH variable in bash Post 302451603 by bakunin on Tuesday 7th of September 2010 11:01:20 AM
Old 09-07-2010
Emulate ksh's FPATH variable in bash
Over time i have developed a library of useful (ksh) functions which i use in most of my scripts. I use the ksh's FPATH variable to locate all these functions and use a standard environment-setting-function to always have the same environment in all my scripts.

Here is how i begin scripts:

Code:
#!/bin/ksh
# foo.ksh

# main()

if [ -z "$DEVELOP" ] ; then                      # set environment
     . /usr/local/lib/ksh/f_env
else
     . ~/lib/f_env
fi

# ... rest of code ....

$DEVELOP is a variable i set if i want to use a local copy of the function library for testing purposes. "/usr/local/lib/ksh/f_env" looks like this:

Code:
if [ -z "$NEVER_USE_THIS_VAR" ] ; then           # recursion protection
    # .... some more settings ...

    if [ -z "$DEVELOP" ] ; then
          typeset -x FPATH="/usr/local/lib/ksh"  # set fnc path for fnc lib
          FPATH="$FPATH:/usr/local/bin"
          FPATH="$FPATH:/usr/local/sbin"
     else
          typeset -x FPATH=~/lib                 # for lib development
     fi

     # ...
     typeset -x NEVER_USE_THIS_VAR="KILROY_WAS_HERE"
fi

This mechanism is quite handy because many functions in the library depend on other functions in the same library and this way all these depencies are solved automatically.

I would like to make this library compatible with the bash shell (ideally i would be able to use these functions from ksh and bash equally), but bash lacks the FPATH mechanism. I came up with the following solution, but obviously it is quite unsatisfactory and i wonder if there is a better way to achieve my goal:

(within f_env(), after setting the FPATH variable: )

Code:
                                                 # simulate FPATH for bash
     if [ -n "$BASH_VERSION" ] ; then
          IFS=:
          for fFPathDir in $FPATH ; do
               for fFFile in $fFPathDir/* ; do
                    if [ $( \
                            sed -n '/^$/d;/^#/!{p;q}' $fFFile |\
                            grep -c '^\(function \)*[^ ][^ ]* ()' \
                          ) -gt 0 ] ; then
                          echo $fFFile
                         . $fFFile
                    fi
               done
          done
     fi

Basically i circle through FPATH, look into every file and if the first non-comment-line begins with "function <some-name> ()" (this is the sed-grep-line) i parse it into the environment. This looks quite clumsy, unreliable and downright ugly, but with my limited knowledge of bash i was not able to find a better solution. Your suggestions are welcome.

bakunin
 

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LEARN ABOUT DEBIAN

libbash

LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME

     libbash -- A bash shared libraries package.

DESCRIPTION

     libbash  is  a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may
     want to load and use in scripts of your own.

     It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries.

     Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1).  A bash shared library that can be  loaded
     using
     ldbash(1) must answer 4 requirments:

     1.     It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash).

     2.     It must contain a line that begins with '#EXPORT='.  That line will contain (after the '=') a list of functions that the library
	    exports.  I.e. all the function that will be usable after loading that library will be listed in that line.

     3.     It must contain a line that begins with '#REQUIRE='.  That line will contain (after the '=') a list of bash libraries that are
	    required for our library.  I.e. every bash library that is in use in our bash library must be listed there.

     4.     The library must be listed (For more information, see ldbashconfig(8)).

   Basic guidelines for writing library of your own:
     1.     Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions.

     2.     Try to declare all variables intended for internal use as local.

     3.     Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with:
		  __<library_name>_
	    For example, internal function myfoosort of hashstash library should be named as
		  __hashstash_myfoosort
	    This helps to avoid conflicts in global name space when using libraries that come from different vendors.

     4.     See html manual for full version of this guide.

AUTHORS

     Hai Zaar <haizaar@haizaar.com>
     Gil Ran <ril@ran4.net>

SEE ALSO

     ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1)

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