global manual page - Built-In Commands

## Tcl8.5.15/Tk8.5.15 Documentation > TclCmd > global

### Tcl/Tk Applications | Tcl Commands | Tk Commands | Tcl Library | Tk Library

### NAME

global - Access global variables

### SYNOPSIS

global varname ?varname ...?

### DESCRIPTION

This command has no effect unless executed in the context of a proc body. If the global command is executed in the context of a proc body, it creates local variables linked to the corresponding global variables (though these linked variables, like those created by upvar, are not included in the list returned by info locals).

If varname contains namespace qualifiers, the local variable's name is the unqualified name of the global variable, as determined by the namespace tail command.

varname is always treated as the name of a variable, not an array element. An error is returned if the name looks like an array element, such as a(b).

### EXAMPLES

This procedure sets the namespace variable ::a::x

    proc reset {} {
        global a::x
        set x 0
    }

This procedure accumulates the strings passed to it in a global buffer, separated by newlines. It is useful for situations when you want to build a message piece-by-piece (as if with puts) but send that full message in a single piece (e.g. over a connection opened with socket or as part of a counted HTTP response).

    proc accum {string} {
        global accumulator
        append accumulator $string \n
    }

### SEE ALSO

namespace, upvar, variable

### KEYWORDS

global, namespace, procedure, variable
Copyright © 1995-1997 Roger E. Critchlow Jr. Copyright © 1993 The Regents of the University of California. Copyright © 1994-1997 Sun Microsystems, Inc.