misc/149335: shell script runs on Linux but not on freebsd

Oliver Fromme olli at lurza.secnetix.de
Fri Aug 6 07:12:57 UTC 2010

Paul Lambert wrote:
 > > Number:         149335
 > > Category:       misc
 > > Synopsis:       shell script runs on Linux but not on freebsd
 > [...]
 > > Environment:
 > FreeBSD BRSINC-VM02.local 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Jul 19 02:36:49 UTC 2010     root at mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64
 > > Description:
 > The script fails on these two lines so far; "stat" and "od"
 > # This won't work with non-GNU stat.
 > FILE_SIZE=`stat --format "%s" "$0"`
 > offset=$(($FILE_SIZE - 4))

As the comment suggests, that command is non-portable and
works with GNU stat (linux) only.  This is not a standard.
The equivalent BSD command line would be:

FILE_SIZE=`stat -f %z "$0"`

I wonder why the script even needs to find out its own size,
and then read binary data from itself?!?  Is this some kind
of "copy protection" or similar tricks?  If so, I suspect
that it is highly non-portable and will be difficult to get
to run on anything else than linux.

 >    # XXX: put extraction in its own function
 >    MAGIC_NUMBER=`od -An -t u4 -N 4 -j $MAGIC_OFFSET "$file" | tr -d ' '`

This command works fine on FreeBSD 8.1.  If it doesn't work
in the context of the script, I suspect that it is caused
by preceding problems that set one of the variables to a
wrong value.

As a work-around, you might try running the script with
/compat/linux/bin/sh instead of /bin/sh.  You need to
enable Linux compatibility ("kldload linux") and install
ports/emulators/linux_base-f10 if you don't have it already.

As this is not a bug in FreeBSD, I suggest that this PR can
be closed.  Do you agree?

Best regards

Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
Handelsregister: Registergericht Muenchen, HRA 74606,  Geschäftsfuehrung:
secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün-
chen, HRB 125758,  Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart

FreeBSD-Dienstleistungen, -Produkte und mehr:  http://www.secnetix.de/bsd

"Unix gives you just enough rope to hang yourself --
and then a couple of more feet, just to be sure."
        -- Eric Allman

More information about the freebsd-bugs mailing list