getcwd

- get pathname of current working directory

Synopsis

#include <unistd.h>

char *getcwd(char *buf, size_t size);

Description

The getcwd() function places an absolute pathname of the current working directory in the array pointed to by buf, and returns buf. The pathname copied to the array contains no components that are symbolic links. The size argument is the size in bytes of the character array pointed to by buf and must be at least one greater than the length of the pathname to be returned.

If buf is not a null pointer, the pathname is stored in the space pointed to by buf.

If buf is a null pointer, getcwd() obtains size bytes of space using malloc(3C). The pointer returned by getcwd() can be used as the argument in a subsequent call to free().

Return Values

Upon successful completion, getcwd() returns the buf argument. If buf is an invalid destination buffer address, NULL is returned and errno is set to EFAULT. Otherwise, a null pointer is returned and errno is set to indicate the error.

Errors

The getcwd() function will fail if:

EFAULT

The buf argument is an invalid destination buffer address.

EINVAL

The size argument is equal to 0.

ERANGE

The size argument is greater than 0 and less than the length of the pathname plus 1.

The getcwd() function may fail if:

EACCES

A parent directory cannot be read to get its name.

ENOMEM

Insufficient storage space is available.

Examples

Example 1 Determine the absolute pathname of the current working directory.

The following example returns a pointer to an array that holds the absolute pathname of the current working directory. The pointer is returned in the ptr variable, which points to the buf array where the pathname is stored.

#include <stdlib.h>
#include <unistd.h>
...
long size;
char *buf;
char *ptr;
size = pathconf(".", _PC_PATH_MAX);
if ((buf = (char *)malloc((size_t)size)) != NULL)
       ptr = getcwd(buf, (size_t)size);
...

Example 2 Print the current working directory.

The following example prints the current working directory.

#include <unistd.h>
#include <stdio.h>

main( )
{
    char *cwd;
    if ((cwd = getcwd(NULL, 64)) == NULL) {
        perror("pwd");
        exit(2);
    }
    (void)printf("%s\n", cwd);
    free(cwd); /* free memory allocated by getcwd() */
    return(0);
}

Usage

Applications should exercise care when using chdir(2) in conjunction with getcwd(). The current working directory is global to all threads within a process. If more than one thread calls chdir() to change the working directory, a subsequent call to getcwd() could produce unexpected results.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

chdir(2), malloc(3C), attributes(5), standards(5)