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Full Discussion: Get variables from expression
Top Forums Shell Programming and Scripting Get variables from expression Post 302901514 by zulfi123786 on Wednesday 14th of May 2014 06:20:41 AM
Old 05-14-2014
Get variables from expression
Hi,

I have a k-shell master script which reads variables that are globally set and this script is modified by users per their requirements and users define few other variables.

In the script few expressions are evaluated which include both global variables and those added by the user, I would like to parse the expressions to get the list of variables used in the expression and check if they are set or not set before evaluating the expression.

The expressions are similiar to SQL where clause and I would like to know if there is any handy utility that parses the expressions and returns only the variables eliminating all constants, relational operators, arithmetic operators and logical operators ?
 

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service

service(8)						      System Manager's Manual							service(8)

NAME

       service - run a System V init script

SYNOPSIS

       service SCRIPT COMMAND [OPTIONS]

       service --status-all

       service --help | -h | --version

DESCRIPTION

       service	runs a System V init script in as predictable an environment as possible, removing most environment variables and with the current
       working directory set to /.

       The SCRIPT parameter specifies a System V init script, located in /etc/init.d/SCRIPT.  The  supported  values  of  COMMAND  depend  on  the
       invoked	script.  service passes COMMAND and OPTIONS to the init script unmodified.  All scripts should support at least the start and stop
       commands.  As a special case, if COMMAND is --full-restart, the script is run twice, first with the stop command, then with the start  com-
       mand.

       service --status-all runs all init scripts, in alphabetical order, with the status command.

EXIT CODES

       service calls the init script and returns the status returned by it.

FILES

       /etc/init.d
	      The directory containing System V init scripts.

ENVIRONMENT

       LANG, TERM
	      The only environment variables passed to the init scripts.

SEE ALSO

       /etc/init.d/skeleton,
       update-rc.d(8),
       init(8),
       invoke-rc.d(8).

								     Jan 2006								service(8)
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