Calling a bash script from a tcl script and returning and exit status

Question

I am attempting to call a bash script from a TCL script and need to get exit status from the bash script or at least pass something back into the TCL script so that I can tell if my script executed successfully. Any suggestions?

Answer 1

See http://wiki.tcl.tk/exec -- click the "Show discussion" button -- there's a very detailed example of how to do exactly what you're asking. What you need though is catch

set status [catch {exec script.bash} output]

if {$status == 0} {
    puts "script exited normally (exit status 0) and wrote nothing to stderr"
} elseif {$::errorCode eq "NONE"} {
    puts "script exited normally (exit status 0) but wrote something to stderr which is in $output"
} elseif {[lindex $::errorCode 0] eq "CHILDSTATUS"} {
    puts "script exited with status [lindex $::errorCode end]."
} else ...

Answer 2

What you want is exec the result of which will be in the return value, be warned however there are lots of gotchas using exec, particularly if you need to do any complex quoting

Answer 3

My experience in tcl is limited to occasional dabbling. However, following links starting with the one in @jk's answer led me to this page which discusses the errorCode variable and related things that might be useful this circumstance. Here's a quick example demonstrating the use of errorCode:

tcl:

set ret_val [catch { exec /bin/bash /path/to/bash_script }]
set errc $errorCode
set ret_val [lindex [split $errc " " ] 2]
puts $ret_val

bash_script, as referenced above:

#!/bin/bash
exit 42

which led to output of:

42