Sticky bit changes the value of the script parameter 0

Question

Hi,
I have a simple shell script:
#!/bin/sh
echo $0It simply returns its own name.
But when I set a sticky bit on this script, it returns
/dev/fd/3
Is it like it is supposed to be? What is the rationale behind such behavior?
I use Solaris 8.
Thanks,
Yevgeny

Answer 1

I have a simple shell script:
#!/bin/sh
echo $0It simply returns its own name.
But when I set a sticky bit on this script, it
returns
/dev/fd/3s/sticky/setuid/
or
s/sticky/setgid/
Is it like it is supposed to be?Yes
What is the rationale behind such behavior?If fixes a race condition for setuid / setgid "#!" interpreter scripts.
Without it, someone could replace the script file during the small
window between the kernel's exec of the interpreter /bin/sh and
the time the /bin/sh shell opens the script.
The fix is to pass a reference to the already open script file using
the /dev/fd/N pseudo filesystem.