GETCWD
NAME SYNOPSIS DESCRIPTION RETURN VALUE CONFORMING TO SEE ALSO
getcwd, get_current_dir_name, getwd - Get current working directory
#include buf, size_t size); char *get_current_dir_name(void); char *getwd(char *buf);
The getcwd() function copies an absolute pathname of the current working directory to the array pointed to by buf, which is of length size.
If the current absolute path name would require a buffer longer than size elements, NULL is returned, and errno is set to ERANGE; an application should check for this error, and allocate a larger buffer if necessary.
If buf is NULL, the behaviour of getcwd() is undefined.
As an extension to the POSIX.1 standard, Linux (libc4, libc5, glibc) getcwd() allocates the buffer dynamically using malloc() if buf is NULL on call. In this case, the allocated buffer has the length size unless size is zero, when buf is allocated as big as necessary. It is possible (and, indeed, advisable) to free() the buffers if they have been obtained this way.
get_current_dir_name, which is only prototyped if _GNU_SOURCE is defined, will malloc(3) an array big enough to hold the current directory name. If the environment variable PWD is set, and its value is correct, then that value will be returned.
getwd, which is only prototyped if _BSD_SOURCE or _XOPEN_SOURCE_EXTENDED is defined, will not malloc(3) any memory. The buf argument should be a pointer to an array at least PATH_MAX bytes long. getwd does only return the first PATH_MAX bytes of the actual pathname.
NULL on failure (for example, if the current directory is not readable), with errno set accordingly, and buf on success. The contents of the array pointed to by buf is undefined on error.
POSIX.1
