I have what is probably the simplest possible useful program in C, under a POSIX system:

#include <unistd.h>
int main(int argc, char* argv[]) {
chdir(argv[1]);
return 0;
}

That's it - no checking for whether argv[1] exists, it just assumes that argv[1] is a real folder and moves you there. When compiled with GCC it doesn't work though - it'll simply exist and "ls" shows no signs that the directory has changed.

How do I fix this?

On Sunday, August 15, 2021 at 10:40:15 AM UTC+3, Bithov Vinu wrote:
> I have what is probably the simplest possible useful program in C, under a POSIX system:
>
> #include <unistd.h>
> int main(int argc, char* argv[]) {
> chdir(argv[1]);
> return 0;
> }
>
> That's it - no checking for whether argv[1] exists, it just assumes that argv[1] is a real folder and moves you there. When compiled with GCC it doesn't work though - it'll simply exist and "ls" shows no signs that the directory has changed.
>
> How do I fix this?

Impossible, under most, if not all, shells running on POSIX -compliant systems.
Child process has no [direct] way to change directory of parent process.

Of course, I have to say that in comp.lanc.c your question is off topic.

On 08/15/2021 09:40 AM, Bithov Vinu wrote:
> I have what is probably the simplest possible useful program in C, under a POSIX system:
>
> #include <unistd.h>
> int main(int argc, char* argv[]) {
> chdir(argv[1]);
> return 0;
> }
>
> That's it - no checking for whether argv[1] exists, it just assumes that argv[1] is a real folder and moves you there. When compiled with GCC it doesn't work though - it'll simply exist and "ls" shows no signs that the directory has changed.
>
> How do I fix this?
>
I believe this is local to the process(your program) and not the bash instance it runs from.

On 2021-08-15, Bithov Vinu <bithov.vinub@gmail.com> wrote:
> I have what is probably the simplest possible useful program in C,
> under a POSIX system:
>
> #include <unistd.h>
> int main(int argc, char* argv[]) {
> chdir(argv[1]);
> return 0;
> }
>
> That's it - no checking for whether argv[1] exists, it just assumes
> that argv[1] is a real folder and moves you there. When compiled with
> GCC it doesn't work though - it'll simply exist and "ls" shows no signs
> that the directory has changed. > > How do I fix this?

Your program does a chdir(), but that doesn't affect the calling program,
probably your shell, so your program doesn't have any effect. You could
exec a shell in your program which would be started in argv[1].

peter

In article <slrnshhhrm.20h.pjvh@xs9.xs4all.nl>,
Peter van Hooft <pjvh@xs9.xs4all.nl> wrote:
>On 2021-08-15, Bithov Vinu <bithov.vinub@gmail.com> wrote:
>> I have what is probably the simplest possible useful program in C,
>> under a POSIX system:
>>
>> #include <unistd.h>
>> int main(int argc, char* argv[]) {
>> chdir(argv[1]);
>> return 0;
>> }
>>
>> That's it - no checking for whether argv[1] exists, it just assumes
>> that argv[1] is a real folder and moves you there. When compiled with
>> GCC it doesn't work though - it'll simply exist and "ls" shows no signs
>> that the directory has changed. > > How do I fix this?
>
>Your program does a chdir(), but that doesn't affect the calling program,
>probably your shell, so your program doesn't have any effect. You could
>exec a shell in your program which would be started in argv[1].

Actually, it does work, if you name your program "cd" and move it into
$HOME/bin (which is on your PATH). Then when you run it from the shell
like this, it will work:

$ cd /tmp
$ ls

The "ls" will list the contents of /tmp.

(Yes, folks, I am kidding)

--
Just for a change of pace, this sig is *not* an obscure reference to
comp.lang.c...

On Sunday, 15 August 2021 at 08:40:15 UTC+1, Bithov Vinu wrote:
> I have what is probably the simplest possible useful program in C, under a POSIX system:

No. You have a totally useless program.

> #include <unistd.h>
> int main(int argc, char* argv[]) {
> chdir(argv[1]);
> return 0;
> }
>
> That's it - no checking for whether argv[1] exists, it just assumes that argv[1] is a real folder and moves you there. When compiled with GCC it doesn't work though - it'll simply exist and "ls" shows no signs that the directory has changed.

It works perfectly. The problem is your lack of understanding.

> How do I fix this?

Learn about unix-style operating systems. This isn't the right newsgroup for that.