Help req. to implement CD command in C

[nikhil_jassi]

I am trying to implement CD command using C language.but the directory is not changing....
This is the code that I have written..... Plz help


#include <unistd.h>
#include<stdio.h>
int main(int argc, char** argv)
{
if (argc == 1) // no args
{
const char* home = getenv("HOME");
chdir(home ? home : "."); // in case HOME is not defined
}
else // arg given (could it be a path?)
{
}
char *directory = "/tr02/mar09ft1/t401579/nik";
int ret;

ret = chdir (directory);
if (ret ==0) // to check that chdir() is working or not//
printf("good");
else
printf("bad");
}

[GNU-Fan]

This chdir command only affects the application started by the shell, i.e. your program, which becomes a separate process. It has no effect on the calling application, the shell.

The shell has the 'cd' command built-in. It is no separate program but more like a control command.

Btw. you seem to have put the curly braces under "else" incorrectly.

[nikhil_jassi]

I got what u exactly want to say....
n the else n brackets mistake i have already corrected....
But plz suggest some other alternative to implement CD command .....

[Rubberman]

This chdir command only affects the application started by the shell, i.e. your program, which becomes a separate process. It has no effect on the calling application, the shell.

The shell has the 'cd' command built-in. It is no separate program but more like a control command.

Btw. you seem to have put the curly braces under "else" incorrectly.

Precisely! The current directory is totally context dependent. For example, if you start a shell within a shell, cd to another directory, then exit that sub-shell, you will find yourself back in the directory you were in before. This is exactly analogous to executing a change directory function in your C program. When it exits, your shell doesn't know that you changed directory at all. So, your exercise is useful if you are writing a shell program, or within the program scope you want to do things in the now-current directory, but it is useless for the calling shell itself.

[nikhil_jassi]

I totally agree with you guyz.... but it is a part of my project....
n anyhow I have to implement it....
so give me any suggestions... I want thee job done....anyhow.....
Plz suggest

[GNU-Fan]

I totally agree with you guyz.... but it is a part of my project....
n anyhow I have to implement it....

What exactly do you want to achieve?

[Rubberman]

What exactly do you want to achieve?

I totally agree with you guyz.... but it is a part of my project....
n anyhow I have to implement it....
so give me any suggestions... I want thee job done....anyhow.....
Plz suggest

Well, if you want the new directory visible outside of the C program you implemented it in, there is actually no way to do so, as far as I am aware.

[GNU-Fan]

Well, if you want the new directory visible outside of the C program you implemented it in, there is actually no way to do so, as far as I am aware.

The shell interpreters could be modified so that they become aware of this.
But the question whether this would be feasible remains as long as the actual goal of nikhil_jassi is unclear.

[Rubberman]

The shell interpreters could be modified so that they become aware of this.
But the question whether this would be feasible remains as long as the actual goal of nikhil_jassi is unclear.

Exactly. Since the system C libraries have a chdir() function to do what he says he wants for use within a particular program, I can only assume that this is some sort of class exercise...