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Is it possible to use chdir() or some other command to change the directory in a thread without affecting the cwd of the other threads ? I'm using pthread.h.

*I'm trying to write a server program that handles multiple client connections and requests. One of the available commands to the client is the 'cd' command.

IrishDog
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3 Answers3

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No, as mentioned by others the current working directory is a per-process property, not per-thread. You can "emulate" a per-thread (or per client, or however you structure your application) current working directory by storing a file descriptor for the "per-thread CWD" and the using the various *at() syscalls specified in POSIX 2008 (openat() etc.) to manipulate paths relative to that directory fd.

janneb
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  • +1 I was going to spitball the *at calls as well. Rather than a definitive "no" they provides some opportunity for OP to reach his goals depending on what he plans. – Duck May 07 '14 at 13:19
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No, it isn't. The current working directory is a process wide setting, not a thread setting.

Your best bet is to explicitly access files in a directory using the full path, rather than changing to that directory in order to do so.

Sean
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  • Could you provide any reference (POSIX, maybe)? The last time I looked for exactly this issue, I found nothing but a vage sense of implementation-defined-ness. – rodrigo May 07 '14 at 11:09
  • As [janneb](http://stackoverflow.com/a/23516195/63743) notes the so-call *at() calls can also be used. Whether they are enough to get OP over the goal line is something he will have to determine. Even using both methods its a bit tricky to emulate being in the cwd. – Duck May 07 '14 at 13:23
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Answering the updated question:

For each client you will need a client structure, which amongst other things (Id, Ip, anything you might consider important) also holds the directory the client is visualizing right now (assuming you do something like this).

So when a request from the client comes you already know in which directory that client works.

Ferenc Deak
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  • Ok, but what if a client try to change the directory? I mean wich command should I use instead of chdir() ? – IrishDog May 07 '14 at 11:08
  • what do you want the client to do in the directory? – Ferenc Deak May 07 '14 at 11:09
  • If you want to list files in a directory and send back to the client: http://stackoverflow.com/questions/4204666/how-to-list-files-in-a-directory-in-a-c-program and just use the directory of the client. – Ferenc Deak May 07 '14 at 11:20