Strange bug in sh quoting on Ultrix (and other BSD systems?)

Strange bug in sh quoting on Ultrix (and other BSD systems?)

Post by Ian Lance Tayl » Mon, 16 Mar 1992 08:52:59

I have encountered a peculiar bug in /bin/sh on Ultrix 4.0 and Ultrix
3.1.  To recreate it, do the following:

    echo "echo foo ran" | foo
    chmod +x foo
    sh -c "\/\f\o\o"

In the final line, I assume that foo is in the root directory.  This
is probably false.  You should put in the directory you are working
in, quoting each character with a backslash.  For example, if you are
in /usr/ian:

    sh -c "\/\u\s\r\/\i\a\n\/\f\o\o"

On Ultrix 4.0 I get something like
    /bin/sh: 8: cannot open
The actual character which appears instead of '8' varies.

On Ultrix 3.1 I get
    /bin/sh: /usr/ian/foo: not found

In both cases it should print
    foo ran

On both systems this works fine with sh5.  It also works on SCO 3.2.2.

If I don't quote some of the characters, it sometimes works.  I've
been unable to find any consistency to it.

I'm doing this extensive quoting in order to safely run a program with
arguments using /bin/sh without having the arguments expanded by the
shell.  Specifically, this is for a UUCP program.  uuxqt tries to run
the program using execve.  If that fails with ENOEXEC, it quotes each
character in the execution request (as shown) and passes it to
/bin/sh.  If uuxqt does not quote all special characters, various
sorts of chicanery become possible.  Quoting every character is not,
of course, necessary, but it's convenient and in any case I don't know
when I will run into this problem.

What I'd like to know is:

    1) Is this a known bug?

    2) Is it specific to Ultrix, or does it happen on other BSD

    3) How do I work around it?

This site does not get, so if you respond only to that
newsgroup please also mail me a copy.

Many thanks.

First person to identify this quote wins a free e-mail message:
``Every so many years he went to England to visit--judging by the
  photographs he showed us--a sundial and some oak trees.''