Hello,

I am writing a C++ program. I need to make some system calls, like ls, cd, etc. I can do "ls" easily by doing system("ls") but when I do system("cd"), it does not change the directory but rather stays in the same one. I have a whole directory tree that I have to traverse through during the course of my entire program but I am not able to make "cd" calls. Is there some other way of doing a cd. For example, I have a home directory and within it, I have a directory called test1 and within it I have directory test2. I am initially in "home" but when I do system("cd test1") or even system("cd home/test1") from within my C++ program, it stays in home and doesn't change to test1. So can anyone please suggest something else that I can do? I know its something very simple but I am not able to find it so far.

Thanks a lot.

Hi salmaz,

try inserting an extra /.
i.e "cd home//test1"

Regards,
Paramesh.

__________________

Don't walk in front of me, I may not follow.
Don't walk behind me, I may not lead.
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you can go up one level by calling:

//==============begin
system ("cd ..");
//==============end

you must type it "cd -space- .."

I am assuming your Linux shell is bash as it is with all distributions that I know about.

When you execute a system(...) call, here's what happens:

The operating system spawns a new shell, executes whatever stuff you have in the argument's string, and then returns to the function that invoked the system() call. Environment changes that were made (including the result of the "cd") can not be passed back upstream. Sorry.

In other words, each system() call starts in whatever directory it was in whenever program execution began.

For test purposes (this works in Linux, or with Windows if you use cygwin/gcc) you could try the following to illustrate the point:


At the program's completion, look in directory temp, and you will find the new file and its contents will be a friendly greeting (to me). So the program did execute the "cd" thing (as it did the other system() things), it just couldn't stay there after the system() call that got it there.

Instead of stringing together a bunch of shell commands with separate system() calls you could create, then invoke, a shell script that executes the sequence, or you could make a single system call that strings together the shell commands, separated by semicolons, or you could write C function calls to do whatever it is that you want to accomplish, or ... (there are probably lots of other ways).

Here's the output of a run that I made with the above example program (the computer name has been changed to protect the innocent):


Regards,

Dave