Re: AS_EXECUTABLE_P again -- summary

[Eric Blake]

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According to Eli Zaretskii on 1/22/2005 9:46 PM:
> 
> Then how can I, with the Cygwin Bash, make a reliable test for the
> existence of `foo'?  Suppose that `foo' doesn't exist, but `foo.exe'
> does--how can one test for that?

If only `foo.exe' exists, then cygwin treats 'foo' and 'foo.exe' as
synonyms.  Likewise, in the case of symlinks, if only `foo.lnk' exists,
cygwin treats 'foo' and 'foo.lnk' as synonyms.  But if both a no-suffix
and suffix version of the file exist, then you must use the suffix to
access the suffix'd file.  Normally this is not a problem; about the only
program that creates both foo and foo.exe to be in the same directory is
libtool (foo is a shell script wrapper that sets $PATH before invoking
foo.exe, and in this case, you really do want the shell wrapper to take
precedence).

The upshot of this is that in the normal case, you don't even have to know
that the suffixes .exe and .lnk exist - just use the short name.  But,
when you DO want to know whether the filename was really short or
suffixed, try again with an explicit suffix.  One reason to need to know
is that `rm foo', to be safe, will not remove foo.exe; you have to use `rm
foo.exe'.  That is probably the biggest reason why Makefiles should use
$(EXEEXT) religiously when targeting cygwin.

Below is a trace that shows the difference between foo and foo.exe.

$ ls
foo.c
$ gcc -o foo foo.c
$ ls
foo.c  foo.exe*
$ ./foo
Hello world
$ ./foo.exe
Hello world
$ test -f foo; echo $?
0
$ test -x foo; echo $?
0
$ touch foo
$ ls
foo  foo.c  foo.exe*
$ test -f foo; echo $?
0
$ test -x foo; echo $?
1
$ test -f foo.exe; echo $?
0
$ test -x foo.exe; echo $?
0

- --
Life is short - so eat dessert first!

Eric Blake             address@hidden
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