01-18-2007
I don't really understand this question. But let's say you have a process running that is a shell. A user has entered the command "date". So no wthe shell would like to run the separate program called "date" and display the results to the user. So the shell will fork and exec the date program. Why? Because that is the only game in town. There is no other way for it to run another program. Either it can fork/exec and thus run the program or it can tell the user "sorry I don't know how to run programs".
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LEARN ABOUT CENTOS
platform::shell
platform::shell(n) Tcl Bundled Packages platform::shell(n)
__________________________________________________________________________________________________________________________________________________
NAME
platform::shell - System identification support code and utilities
SYNOPSIS
package require platform::shell ?1.1.4?
platform::shell::generic shell
platform::shell::identify shell
platform::shell::platform shell
_________________________________________________________________
DESCRIPTION
The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.
This package allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
requirement is that the other shell (identified by its path), is actually executable on the current machine.
While for most platform this means that the architecture of the interrogated shell is identical to the architecture of the running shell
this is not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.
For applications like a code repository it is important to identify the architecture of the shell which will actually run the installed
packages, versus the architecture of the shell running the repository software.
COMMANDS
platform::shell::identify shell
This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.
platform::shell::generic shell
This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.
platform::shell::platform shell
This command returns the contents of tcl_platform(platform) for the specified Tcl shell.
KEYWORDS
operating system, cpu architecture, platform, architecture
platform::shell 1.1.4 platform::shell(n)