'How to set environment variables in tcl?

When I source my .cshrc file and run the Tcl script it is working fine:

$ source .cshrc-sample
$ tclsh invoke.tcl

Following is the .cshrc file:

setenv AUTOTEST "/auto/isbutest/frt"
setenv ATS_EASY "$AUTOTEST"
setenv ATS_USER_PATH "$AUTOTEST"
setenv PATH "${AUTOTEST}/bin:${PATH}"

But when I tried setting the environment variable in Tcl itself and run the script, I get the following error:

$ tclsh invoke.tcl
can't find package ha
    while executing
"package require ha"
    (file "invoke.tcl" line 8)

My Tcl script - invoke.tcl:

global env

set env(AUTOTEST) "/auto/isbutest/frt"
set env(ATS_EASY) "/auto/isbutest/frt"
set env(ATS_USER_PATH) "/auto/isbutest/frt"
set env(PATH) "$env(PATH):/auto/isbutest/frt/bin:";
package require ha

How can I run the script without sourcing the .cshrc?

The thing is setting environment variable is not possible using scripts, the lifetime of the variable is within the runtime of the script. When I tried printing the PATH variable it shows what is needed, but I don't know why it is not working. Is there any other workaround for this?

shellenvironment-variablestcl


Solution 1:[1]

There's a few possibilities. The key things to look at are whether there are any other environment variables that you've missed out, whether the Tcl auto_path global variable is correct immediately before the package require, and whether there is anything else going on.

The easiest way from the Tcl side is to add:

puts "auto_path=$auto_path"
parray env

immediately before the package require that has the error. That should print out plenty of information. (Pay particular attention to if you are setting the TCL_LIBRARY or TCLLIBPATH environment variables differently.)

Aside from that, it's possible that there is something set in the ~/.tclshrc file, which is only sourced in interactive mode (it happens before you get your prompt). That could cause observable changes. Another option is if the ha package's pkgIndex.tcl script is written to use abbreviated commands, which only work when Tcl is in interactive mode. Errors in the package index definition script will make the code that describes how to actually load/source the package's implementation not register, and could give you the error state you see. If the script is assuming it can use abbreviations, fix it as that's always a bug. Abbreviations are a convenience when using Tcl interactively, and should never be put in proper saved code.

You might want to check whether the list of packages is complete. Use this code for that:

catch {package require NoSuchPackage}; # Force immediate population of the list of packages
puts Packages:\n\t[join [lsort -dictionary [package names]] \n\t]

Again, put this in after any setting of global variables and before the problem package require.

Solution 2:[2]

In side tcl script, you can simply do setenv as, setenv AUTOTEST="/auto/isbutest/frt".

if you want to set a variable, use set VARNAME "/auto/isbutest/frt".

if you want to get any environment variable, use $::env(AUTOTEST).

and any variable declared using set command can be accessed using $VARNAME.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Donal Fellows
Solution 2 nillu

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