How to export variables from Bash into tcl?

Question

I have variables A, B, and C.

I have written

export A=$A
export B=$B
export C=$C

Not sure how to carry the variables over into a tcl script. What I currently have written in the tcl script is

puts "$A == $::env(A)"
puts "$B == $::env(B)"
puts "$C == $::env(C)"

But that doesn't work. I have tried with and without the first $.

Answer 1

Either way is meant to work:

$ export A="a"
$ echo "puts $::env(A)" | tclsh
a

or

$ export B="b"; echo "puts $::env(B)" | tclsh
b

or

$ echo "puts $::env(C)" | C="c" tclsh
c

Answer 2

There are two ways. Either you export the variable (there are a few ways to do that) or you assign it as part of the call to tclsh . Using export :

export B="b"
echo 'puts "the B environment variable is $::env(B)"' | tclsh

B="b"
export B
echo 'puts "the B environment variable is $::env(B)"' | tclsh

Assigning as part of the call (NB: no semicolons and the variable assignment is close to the actual call to tclsh ):

echo 'puts "the B environment variable is $::env(B)"' | B="b" tclsh

For anything complex or large, try to avoid passing it via environment variables (or command line arguments). Using files works better in those cases. For anything secret , DO NOT use either command line arguments or environment variables as neither is a secure communication mechanism, but files (with appropriate permissions, including on the containing directory) are sufficiently secure.