Debug tclsh

De HurdFr_Wiki.

tclsh debugging

Goal

tclsh is used in autotools' ./configure to get the found TCL version. The problematic line is this one:

 TCL_VERSION_FOUND=`echo 'puts [info tclversion]' | $TCLSH`

$TCLSH contains the full path to tclsh, which is: /usr/bin/tclsh; we'll use the binary name from now.

When trying this:

 echo 'puts [info tclversion]' | tclsh

we get '8.4' as expected (tcl8.4 is the package we're considering).

But when trying this:

 A=`echo 'puts [info tclversion]' | tclsh`; echo $A

that hangs on hurd-i386. :-s

The first thing we can think about is a wrong use of stdin by tclsh. After having read the manual, we try that:

 T=`mktemp`
 echo 'puts [info tclversion]' > $T
 tclsh $T

which gives '8.4' too, but we've got:

 A=`tclsh $T`

still hangs on hurd-i386...

stdout?

After some tests, I found out that stdout could be involved. Quick summary of what's working or not. $T is a file containing the following instruction: puts [info tclversion]

Command	hurd-i386	powerpc
tclsh $T	8.4	8.4
V=`tclsh $T`; echo $V	(hangs)	8.4
V=`tclsh $T > /tmp/test; cat /tmp/test`; echo $V	8.4	8.4
V=`tclsh $T [pipe] cat`; echo $V	(hangs)	8.4
V=`tclsh $T [pipe] cat > /tmp/something`; echo $V	(hangs)	(outputs nothing)