I am trying to use a system call in Sun OS 4.1.3, chroot. Below is the
pseudo code, the actual code of which compiles and runs without errors but
does not work, ie, change the root directory.

#include <stdio.h>
#include <string.h>
main()
{
int chroot();
char dir[80];

                strcpy(dir,"new/directory");
                chroot(dir);

Is there something I am not doing in order to make a system call? I would
appreciate any help you can provide. Thanks in advance.

Regrards....John

  you should check the return value of chroot(); if it fails, call perror()
to see why.  this will provide your answer (so would looking at the manpage).

d.

--
No dogs were harmed in the creation of this .sig.   A cat got sick,
and somebody shot a duck, but that's it.

1. How do you know it fails?  You're not checking its return value and
   the program terminates before doing anything meaningful.

2. Are you root when executing the program?

3. Checking errno if chroot() doesn't return 0 will give you a clue about
   what went wrong.

4. If you expect the program to change the root directory of the shell
   which invoked it, this will never happen, chroot() will affect only
   the process that called it.

This is a Unix specific question, so it doesn't belong to c.l.c.  Post
such questions to comp.unix.programmer.

Dan
--
Dan Pop
CERN, CN Division

Mail:  CERN - PPE, Bat. 31 R-004, CH-1211 Geneve 23, Switzerland

    John> I am trying to use a system call in Sun OS 4.1.3,
    John> chroot. Below is the pseudo code, the actual code of which
    John> compiles and runs without errors but does not work, ie,
    John> change the root directory.

    John> #include <stdio.h>
    John> #include <string.h>
    John> main()
    John> {
    John> int chroot();
    John> char dir[80];
    John>            strcpy(dir,"new/directory");
    John>            chroot(dir);
    John> }

There's nothing wrong with this code (although BTW you can write
'chroot("new/directory")' directly), but the chroot function changes
the root directory for the current process and all children of the
current process. If you run this program from your shell it won't
change your shell's root directory--that seems to be what you were
expecting.

Jake

(Followups to comp.unix.programmer)

I trust you are running as superuser (i.e., root).
You may need to chdir() to the directory before you chroot() to it.

P.S. Next time you have a question about a SunOS system call, you
might want to post it to comp.unix.programmer, comp.unix.questions
or comp.sys.sun.misc.