How to set environment variable for parent process (Linux shell) in TCL

[ZeroName]

Dear Sir:

How can i set an environment variable in TCL and the variable can be used in its parent process (for example: csh)?

in csh:
setenv a 123

in tcl:
set env(a) 456

after exiting tcl, i wish the variable, a is "456"

Please help me to solve the problem, thanks~

[Colin Macleod]

On Tuesday, 14 February 2017 08:16:42 UTC, ZeroName wrote:
> How can i set an environment variable in TCL and the variable can be used in its parent process (for example: csh)?
>

This cannot be done, in Tcl or any other language. It is a property of unix processes that a child process has no access to the environment of its parent process.

Colin.

[Andreas Leitgeb]

There are of course ways around it, if the calling shell expects to receive
environment data from the child.

The child (tcl-script) would then write the environment to stdout (and
nothing else!) and the outer shell (csh is evil; use bourne shells!):

zsh, bash, ksh or sh:
eval "`script.tcl`"

script.tcl:
#!/usr/bin/env tclsh
puts "export FOO; FOO=foo"
puts "export BAR; BAR='sn afu'"

PS: child process is responsible for protecting meta characters and blanks
in the values.