Getting absolute path of a file

How can I convert a relative path to an absolute path in C on Unix? Is there a convenient system function for this?

On Windows there is a GetFullPathName function that does the job, but I didn't find something similar on Unix...

Use realpath().

The realpath() function shall derive, from the pathname pointed to by file_name, an absolute pathname that names the same file, whose resolution does not involve '.', '..', or symbolic links. The generated pathname shall be stored as a null-terminated string, up to a maximum of {PATH_MAX} bytes, in the buffer pointed to by resolved_name.

If resolved_name is a null pointer, the behavior of realpath() is implementation-defined.


The following example generates an absolute pathname for the file identified by the symlinkpath argument. The generated pathname is stored in the actualpath array.

#include <stdlib.h>
...
char *symlinkpath = "/tmp/symlink/file";
char actualpath [PATH_MAX+1];
char *ptr;


ptr = realpath(symlinkpath, actualpath);

File getAbsolutePath() method in Java with Examples, Then we cd "$(dirname "$1") into this relative dir; && pwd -P and get absolute path for it. -P option will avoid all symlinks; After that we append� The java.io.File.getAbsolutePath () method returns the absolute pathname string of this abstract pathname.

Try realpath() in stdlib.h

char filename[] = "../../../../data/000000.jpg";
char* path = realpath(filename, NULL);
if(path == NULL){
    printf("cannot find file with name[%s]\n", filename);
} else{
    printf("path[%s]\n", path);
    free(path);
}

How to get full path of a file?, If the file object is created using a relative path, the absolute pathname is resolved in a system-dependent way. On UNIX systems, a relative pathname is made� * To get absolute path of the file use, * String getAbsolutePath () method of File class.

Also try "getcwd"

#include <unistd.h>

char cwd[100000];
getcwd(cwd, sizeof(cwd));
std::cout << "Absolute path: "<< cwd << "/" << __FILE__ << std::endl;

Result:

Absolute path: /media/setivolkylany/WorkDisk/Programming/Sources/MichailFlenov/main.cpp

Testing environment:

setivolkylany@localhost$/ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 8.6 (jessie)
Release:    8.6
Codename:   jessie
setivolkylany@localhost$/ uname -a
Linux localhost 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u2 (2016-10-19) x86_64 GNU/Linux
setivolkylany@localhost$/ g++ --version
g++ (Debian 4.9.2-10) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Java File Path, Absolute Path and Canonical Path, Publications\TravelBrochure.pdf, A relative path to file in a directory that is a GetFullPath(String, String) method to get an absolute path from a� getAbsolutePath(): This method returns path which is a fully qualified path (after resolving the path relative to the current directory, if the relative path was used while creating the File object). getCanonicaPath(): This method returns the path which is similar to the absolute path but it also converts .

There is also a small path library cwalk which works cross-platform. It has cwk_path_get_absolute to do that:

#include <cwalk.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
  char buffer[FILENAME_MAX];

  cwk_path_get_absolute("/hello/there", "./world", buffer, sizeof(buffer));
  printf("The absolute path is: %s", buffer);

  return EXIT_SUCCESS;
}

Outputs:

The absolute path is: /hello/there/world

File path formats on Windows systems, It is not just a marker, but already a full qualified address, a path. Type cd / in your unix console and you will get to the root directory. Exactly the same is true for all� The absolute path includes all information required to locate a file or directory on a system. The file or directory specified by path is not required to exist. For example, if c:\temp ewdir is the current directory, calling GetFullPath on a file name such as test.txt returns c:\temp ewdir\test.txt. The file need not exist.

Relative and absolute paths, in the file system and on the web , Python code example 'Get the absolute path of a file' for the package os, powered by Kite. The result is a list of org.apache.hadoop.fs.Path elements which I need to process in the sub-sequent steps. Hence, I need to full path. My question is: what is the best way to get the full absolute path. So far, I use a recursive method to create the path string (Scala):

os - Get the absolute path of a file - Python code example, An absolute path refers to the complete details needed to locate a file or folder, starting from the root element and ending with the other subdirectories. Absolute � Relative File Paths. A relative file path points to a file relative to the current page. In the following example, the file path points to a file in the images folder located at the root of the current web:

What is an Absolute Path?, There's no way around it, you have to get absolute path to the file or folder where items are going to be stored or used by the application. You are thinking to� getAbsolutePath (): This file path method returns the absolute path of the file. If File is created with absolute pathname, it simply returns the pathname. If the file object is created using a relative path, the absolute pathname is resolved in a system-dependent way.

Comments
  • The 'plus one' is not necessary, thuogh it won't do any harm.
  • GetFullPathName on Windows works for non-existant files as well. realpath requires the path to exist. This kind of sucks when you want to create a path or file.
  • The actual path contains the absolute path, but what does ptr contain?
  • @JonathanLeffler: PATH_MAX is "The uniform system limit (if any) for the length of an entire file name", so excludes the terminating nul which is added by realpath. The +1 is therefore required.
  • @EML +1 is not required. From POSIX limits.h rationale: "IEEE PASC Interpretation 1003.1 #15 addressed the inconsistency in the standard with the definition of pathname and the description of {PATH_MAX}, allowing application developers to allocate either {PATH_MAX} or {PATH_MAX}+1 bytes. The inconsistency has been removed by correction to the {PATH_MAX} definition to include the null character. With this change, applications that previously allocated {PATH_MAX} bytes will continue to succeed."
  • 100K for a path?! surely 5K is enough? or PATH_MAX?