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Top Forums Shell Programming and Scripting Problem with eval a generated and interpreted variable name and its value Post 302897899 by Corona688 on Wednesday 16th of April 2014 05:47:54 PM
Old 04-16-2014
eval is almost never the answer. The same usually goes for dynamic variable names. If you find yourself using either, you've taken a wrong turn somewhere.

You can use a here-document to safely turn your variables into strings. Much better than eval.

Code:
echo "cat <<EOF" >> /tmp/$$
# copy into /tmp/$$ removing backticks and () to prevent accidental/malicious execution of commands
tr -d '`()' < configfile >> $/tmp/$$
echo "EOF" >> /tmp/$$

. /tmp/$$ > /tmp/$$-1

rm /tmp/$$

It works by creating a file like this:

Code:
cat <<EOF
bookmark
bookmark
bookmark
EOF

...and running it in your shell to create another file.

/tmp/$$-1 should now contain the same text as your GTK file with $VARIABLE names substituted.

TIP: You can do ${VARNAME}stuff instead of $VARNAME stuff in your config file. The shell will look for the { } so you won't need spaces to separate them out.

Last edited by Corona688; 04-16-2014 at 07:04 PM..
This User Gave Thanks to Corona688 For This Post:
 

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variable(n)						       Tcl Built-In Commands						       variable(n)

__________________________________________________________________________________________________________________________________________________

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(n), namespace(n), upvar(n) KEYWORDS
global, namespace, procedure, variable Tcl 8.0 variable(n)
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