Re: #!/usr/bin/env tclsh

[Gary Thomas <gary at mlbassoc dot com>]

John Dallaway wrote:
> Hi Bart and Gary
> 
> Bart Veer wrote:
> 
>>>>>>> "John" == John Dallaway <john@dallaway.org.uk> writes:
>>     John> This patch simplifies the #! magic used to invoke Tcl
>>     John> scripts by using "/usr/bin/env tclsh" to find the tclsh
>>     John> executable. Very old Cygwin installations providing only
>>     John> tclsh83.exe or cygtclsh80.exe are no-longer supported.
>>     John> Checked-in.
>>
>> Actually, this patch has broken things in various ways. Consider e.g.
>> file2c.tcl in the romfs package. The CDL invokes this using e.g.:
>>
>>   sh file2c.tcl testromfs_le.bin testromfs_le.h
>>
>> With the old magic this still worked fine because sh would ignore the
>> #! at the start completely and move on to the 'exec sh -c' on line 3.
>> With the new '#!/usr/bin/env tclsh' the sh invocation ignores the
>> #! comment on line 1 so ends up trying to run the whole Tcl script as
>> a shell script. Needless to say this is not very successful.
>>
>> io/framebuf is similarly affected. services/memalloc/common is not. I
>> have not yet checked all the other packages that use Tcl scripts.
> 
> Good catch.
> 
>> Possible solutions are:
>>
>> 1) revert the change
>> 2) remove the 'sh' bits from the relevant CDL scripts, treating the
>>    Tcl script as plain executables.
>> 3) make the CDL invoke /usr/bin/env tclsh directly, treating the
>>    Tcl scripts as Tcl scripts.
>>
>> (1) would be a bad move. I think I would prefer (3) to (2).
> 
> Option 2 presents problems with CVS checkouts of the eCos repository
> where execute permissions on the various Tcl scripts cannot be assumed.
> 
> I agree with Bart that invoking "/usr/bin/env tclsh" within the various
> CDL custom rules doesn't gain us anything. It seems entirely reasonable
> to assume that tclsh is on the PATH and users will get an intelligible
> error message if it is not. In the case of heapgen.tcl, I simply
> modified the custom make rule to invoke "tclsh" rather than "sh" and I
> suggest we do the same with the other scripts. Are you OK with this
> proposal?
> 
> If we can agree on this, I am happy to identify and implement these changes.

Sure - whatever it takes to make it work [again].  Too bad "sh"
is being too "smart" about this...


-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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