When I do this with /bin/zsh, it does the right thing. The source command
in the bltwish shell gives me ccp4i.
When I run the commands interactively in bash or sh (which is bash on os
x), the command
exec ${CCP4I_TCLTK}/bltwish "$0" -- ${1+"$@"}
terminates the shell session instead of turning it into a bltwish shell.
So I think your process is getting killed before you look at the cat in
the box. If it is a question of ${CCP4I_TCLTK} not getting assigned, the
error you should see looks like this:
bash: /bltwish: No such file or directory
bash: exec: /bltwish: cannot execute: No such file or directory
or
sh: /bltwish: No such file or directory
sh: exec: /bltwish: cannot execute: No such file or directory
Likewise, with quantum mechanics, the mysteries disappear if you allow
that the probability function is an objective statement about where a
particle might be located, rather than a subjective statement about our a
priori knowledge of the particle's location (i.e., you reject
wave-particle duality in favor of a particle interpretation).
On Sun, July 26, 2009 2:34 pm, James Stroud wrote:
> Hello All,
>
> It seems that sh has a variable that exists and doesn't exist at the
> same time (see my shell session below). Isn't such transition between
> existence and non-existence reserved for quantum mechanics and eastern
> philosophy? My guess is that sh has become more vigilant about
> security and the exec statement. Can anyone venture a better guess as
> to how the output below might happen? What's the best way around
> this? But the real question is: Can the people at ccp4 look at this
> and make changes to the code base before these kinds of security
> features become more commonplace (for the good reason to prevent
> injection attacks)?
>
> For example:
> http://www.theregister.co.uk/2009/07/21/critical_ddwrt_router_vuln/
>
> Here is my shell session:
>
> chernev 10% cat `which ccp4i`
> #!/bin/sh
> # Start ccp4i interface
> # \
> echo CCP4I_TCLTK is $CCP4I_TCLTK
> exec ${CCP4I_TCLTK}/bltwish "$0" -- ${1+"$@"}
> source [file join $env(CCP4I_TOP) bin ccp4i.tcl]
> chernev 11%
> chernev 12% ccp4i
> CCP4I_TCLTK is /usr/local/X11/bin
> Error in startup script: can't read "CCP4I_TCLTK": no such variable
> while executing
> "exec ${CCP4I_TCLTK}/bltwish "$0" -- ${1+"$@"}"
> (file "/usr/local/ccp4-6.1.1/bin/ccp4i" line 5)
>
William G. Scott
Contact info:
http://chemistry.ucsc.edu/~wgscott/
