GETCWD(3C) Standard C Library Functions GETCWD(3C)

getcwd — get pathname of current working directory

#include <unistd.h>

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

The () function returns a pointer to a buffer containing the absolute pathname of the current working directory. The returned pathname contains no components that are symbolic links.

When buf is not NULL, the absolute pathname will be written into buf and size represents the length in bytes of buf. If the length of the pathname and nul terminator exceeds size, nothing will be written and () will return NULL. Otherwise, getcwd() returns buf.

When buf is NULL then () will allocate memory in which to store the pathname of the current working directory. If size is non-zero, then size bytes will be allocated. If the length of the pathname and nul terminator exceeds size, the memory will be freed and getcwd() will return NULL. If size is zero, then getcwd() will attempt to allocate enough space to hold the pathname. In both cases, it is the caller's responsibility to free the returned buffer with the free(3C) function.

Upon successful completion, the getcwd() function returns a pointer to a buffer containing the pathname. Otherwise, NULL is returned and errno is set to indicate the error.

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

int
main(void)
{
	char *cwd;

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

The getcwd() function will fail if:

The buf argument points to an invalid address.
The buf argument is not NULL and the size argument is 0.
The pathname (including its terminating nul character) is too long to fit into the provided (or allocated) buffer.
A parent directory cannot be read to get its name.
Insufficient storage space is available.

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

chdir(2), free(3C), attributes(7), standards(7)

February 27, 2021 OmniOS