07-28-2009
shell variables advanced
Hi all, i have more questions but its all about variables so lets begin
1st, is possible to list all variables ?
Command env display only shell variables, but what if i declared another variable? Command set display more variables but not defined by me.
2nd, what difference is between set and env ?
3rd, lets say i declared variable which contains whitespaces, or i have variable which contains whitespaces for example IFS. When i type echo $IFS i see nothing, so i dont know if is declared or if contain white spaces.
Is possible to write white spaces in C format (\n \r \t ...) ?
4th what is difference between sourcing and exporting variable ?
PS: i saw declaration of IFS in set command (IFS=$' \t\n')
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LEARN ABOUT OPENDARWIN
variable
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 locals.) 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.
SEE ALSO
global(n), namespace(n), upvar(n)
KEYWORDS
global, namespace, procedure, variable
Tcl 8.0 variable(n)