[bash] command line substitution with environmental variables

03-07-2010

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bash dynamic variables

For future reference, this is an approximate
representation of the system so far. The method
suggested works and generates identical output
whilst processing.

I may have been overwhelmed with a working
system that I may have began to think a little
too far ahead with the possibilities when trying
to incorporate it into a function. However, I
still think it *might* be of some interest.

Code:

#!/bin/bash

declare -a FLAGS
FLAGS[0]="CFLAGS=\"-arch x86_64 -g -Os -pipe -no-cpp-precomp\""
FLAGS[1]="LDFLAGS=\"-arch x86_64 -bind_at_load\""

declare -a OPTION
OPTION[0]="./configure"
OPTION[1]="--bindir=/usr/local/bin"
OPTION[2]="--datarootdir=/usr/local/share"
OPTION[3]="--mandir=/usr/local/man"

declare -a CONFIG
declare do_flags=true

## check if array is not null
if [ -n "${FLAGS}" ]; then
## check if flags prefix ./configure
    if $do_flags
        then CONFIG=( "${FLAGS[@]}" )
        fi
        fi

## append options to array
CONFIG=( "${CONFIG[@]}" "${OPTION[@]}" )

## check contents of array
echo "${CONFIG[@]}"
## execute contents of array (disabled)
## eval "${CONFIG[@]}"

## check dynamic variables
eval "${FLAGS[@]}"
echo "CFLAGS=$CFLAGS"
echo "LDFLAGS=$LDFLAGS"

ASGR

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variable(1T) Tcl Built-In Commands variable(1T) __________________________________________________________________________________________________________________________________________________ NAME
variable - create and initialize a namespace variable SYNOPSIS
variable ?name value...? name ?value? _________________________________________________________________ DESCRIPTION
This command is normally used within a namespace eval command to create one or more variables within a namespace. Each variable name is initialized with value. The value for the last variable is optional. If a variable name does not exist, it is created. In this case, if value is specified, it is assigned to the newly created variable. If no value is specified, the new variable is left undefined. If the variable already exists, it is set to value if value is specified or left unchanged if no value is given. Normally, name is unqualified (does not include the names of any containing namespaces), and the variable is created in the current namespace. If name includes any namespace qualifiers, the variable is created in the specified names- pace. If the variable is not defined, it will be visible to the namespace which command, but not to the info exists command. If the variable command is executed inside a Tcl procedure, it creates local variables linked to the corresponding namespace variables (and therefore these variables are listed by info vars.) In this way the variable command resembles the global command, although the global command only links to variables in the global namespace. If any values are given, they are used to modify the values of the associated namespace variables. If a namespace variable does not exist, it is created and optionally initialized. A name argument cannot reference an element within an array. Instead, name should reference the entire array, and the initialization value should be left off. After the variable has been declared, elements within the array can be set using ordinary set or array commands. EXAMPLES
Create a variable in a namespace: namespace eval foo { variable bar 12345 } Create an array in a namespace: namespace eval someNS { variable someAry array set someAry { someName someValue otherName otherValue } } Access variables in namespaces from a procedure: namespace eval foo { proc spong {} { # Variable in this namespace variable bar puts "bar is $bar" # Variable in another namespace variable ::someNS::someAry parray someAry } } SEE ALSO
global(1T), namespace(1T), upvar(1T) KEYWORDS
global, namespace, procedure, variable ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWTcl | +--------------------+-----------------+ |Interface Stability | Uncommitted | +--------------------+-----------------+ NOTES
Source for Tcl is available on http://opensolaris.org. Tcl 8.0 variable(1T)

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