Absolute path

qspares · 10-24-2004, 11:52 AM

Hi! All:
Is there a system funtion to convert a relative path to an absolute path?
For example: If my current working directory is: "/home/abc/xyz"
when I pass: "../", it will return me: "/home/abc"

Thanks!

Komakino · 10-24-2004, 12:09 PM

The environment variable $PWD will return the absolute path to your currect working directory...other than that nothing springs to mind. Perhaps if you told us what you want to do with it?

Paxmaster · 10-24-2004, 12:12 PM

that easy just type "cd" my it self it will return to what ever you home dir

i think that's what u were trying to say

rjlee · 10-24-2004, 12:17 PM

Using BASH, you can just do

Code:

`pwd`$path

The backticks (`) enclose an external command; the results of which (on standard-output) are used in place of the string. So `pwd` will always give you the current working directory (that's what the pwd command does). The relative path can just be appended to it.

In C, you can do something similar:

Code:

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
void getdirname(char * relpath) {
    char * abspath = getcwd(NULL,0);
    char * buffer = (char*)malloc(strlen(abspath)+strlen(relpath)+1);
    sprintf(buffer,"%s%s",abspath,relpath);
    free(abspath);
    return buffer;
}

You should call free() on the return value to deallocate the memory.

I haven't tested that but you get the idea.

Komakino · 10-24-2004, 12:37 PM

Quote:

Originally posted by Paxmaster
that easy just type "cd" my it self it will return to what ever you home dir

i think that's what u were trying to say

I don't think that's what he's after...

qspares · 10-24-2004, 01:03 PM

Sorry I didn't make it clear, I mean in C programming, not in shell.
Let's say I have two directories:
/aaa/bbb1/ccc1
/aaa/bbb2/ccc2

If I am in ccc1, then ../../bbb2 should return me:
/aaa/bbb2

Or, if I pass: /aaa/bbb1/../bbb2, the function should still return me:
/aaa/bbb2

The purpose is just to display the directory name correctly. I remember in
Java there is something called "canonical path", wonder if C has a similar
thing?

gloriant · 10-02-2007, 03:11 AM

Quote:

Originally Posted by qspares

The purpose is just to display the directory name correctly. I remember in
Java there is something called "canonical path", wonder if C has a similar
thing?

Probably you're looking for realpath.

Code:

realpath - resolve pathname
SYNOPSIS
#include <stdlib.h>

char *realpath(const char *file_name, char *resolved_name);