Re: gnulib-tool: possible bug in detection of a working `echo' command

[Bruno Haible]

Hi Stefano,

> The bug is in this command:
>   $CONFIG_SHELL -c 'echo '\t' | grep t > /dev/null'
> which should check if $CONFIG_SHELL (when set) has a usable `echo'
> command.  But the way it's written, that test *always* succeds,
> even if $CONFIG_SHELL has a broken `echo' builtin.  This is caused
> by the  fact that the `\t' in there is *not* quoted (even if at a first
> glace it might seem to be), and thus the backslash is removed by the
> shell  *before* running $CONFIG_SHELL, which then run a test like:
>   echo t | grep t > /dev/null
> which of course succeds.
> 
> To properly check the `echo' builtin of $CONFIG_SHELL, the command 
> should be rewritten as e.g.:
>   $CONFIG_SHELL -c "echo '\\t' | grep t > /dev/null"

You're entirely right. I've applied your fix as follows. (The "tiny change"
phrase in the ChangeLog entry should not upset you: it merely means that we
don't need a formal copyright assignment for this change.) Thanks!


2009-08-31  Stefano Lattarini  <address@hidden>  (tiny change)

        * gnulib-tool: Fix test whether $CONFIG_SHELL has a working 'echo'
        command.

--- gnulib-tool.orig    2009-08-31 23:01:16.000000000 +0200
+++ gnulib-tool 2009-08-31 22:57:06.000000000 +0200
@@ -703,7 +703,7 @@
    && test "X$1" != "X--no-reexec" \
    && test -n "$CONFIG_SHELL" \
    && test -f "$CONFIG_SHELL" \
-   && $CONFIG_SHELL -c 'echo '\t' | grep t > /dev/null'; then
+   && $CONFIG_SHELL -c "echo '\\t' | grep t > /dev/null"; then
   exec $CONFIG_SHELL "$0" --no-reexec "$@"
   exit 127
 fi