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Full Discussion: Interpreting Logicals/Environment Variables using the read command
Top Forums Shell Programming and Scripting Interpreting Logicals/Environment Variables using the read command Post 302320196 by kingpin2502 on Wednesday 27th of May 2009 09:58:35 AM
Old 05-27-2009
Interpreting Logicals/Environment Variables using the read command
Hi All

I have something that from the outset seems really trivial but in practice is not quite working.

I have the following code sample in my shell script which illustrates the problem

Code:
echo "enter home directory"
read home
mkdir $home/newdir

The user then enters a logical $HOME in the prompt. This is what is displayed on the screen

Code:
enter home directory
$HOME
mkdir: cannot create directory `$HOME/newdir': No such file or directory

If I type the full name into the prompt, it works fine. But this isn't ideal as in the real script, the directory structure could be 10 directories deep. Typing the full path could lead to potential issues.

Is there some way for the read command to interpret environment variables?

Thanks
 

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LEARN ABOUT DEBIAN

platform::shell

platform::shell(3tcl)					       Tcl Bundled Packages					     platform::shell(3tcl)

__________________________________________________________________________________________________________________________________________________

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(3tcl)
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