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I'm trying to source a some.cshrc during TCL script execution. I get no error but the variables set in some.cshrc are not passed back to the shell.

When writing it like: source some.cshrc I'm getting an error. Then I tried: exec /bin/csh -c "source some.cshrc"

Please advise

Kay Lis
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  • It's a completely different language. That's… really very tricky. What was the error message? – Donal Fellows Apr 29 '19 at 13:36
  • Possible duplicate of [Set a parent shell's variable from a subshell](https://stackoverflow.com/questions/15541321/set-a-parent-shells-variable-from-a-subshell) – ceving Apr 29 '19 at 14:17
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    You can not set a variable in the parent process from a child process. – ceving Apr 29 '19 at 14:18
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    How complex is the process of setting those variables? If it's simply `set x=y`, then you can read the file in Tcl and parse out the values. If it's more complex, like using backticks, then you'll have to spawn a csh, source the file, and print out the variable/value pairs. – glenn jackman Apr 29 '19 at 14:30

1 Answers1

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Since Csh and Tcl are two completely different languages, you cannot simply load a Csh file in a Tcl script via a source command.

You can think of a workaround instead. Let us assume you want to load all the variables set with a setenv command. Example contents of some.cshrc file could look something like this:

setenv EDITOR vim
setenv TIME_STYLE long-iso
setenv TZ /usr/share/zoneinfo/Europe/Warsaw

You can write a Tcl script which reads this file line by line and searches for setenv commands. You can then reinterpret the line as a list and set an appropriate variable in a global namespace via an upvar command.

#!/usr/bin/tclsh

proc load_cshrc {file_name} {
  set f [open $file_name r]
  while {[gets $f l] >= 0} {
    if {[llength $l] == 3 && [lindex $l 0] eq "setenv"} {
      upvar [lindex $l 1] [lindex $l 1]
      set [lindex $l 1] [lindex $l 2]
    }
  }
  close $f
}

load_cshrc "some.cshrc"
puts "EDITOR = $EDITOR"
puts "TIME_STYLE = $TIME_STYLE"
puts "TZ = $TZ"

Please note, that since we do not run a Csh subshell any variable substitutions in the Csh script would not occur.

Maciej Stanek
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