NAME

       getcwd, getwd, get_current_dir_name - get current working directory

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       char *getcwd(char buf[.size], size_t size);
       char *get_current_dir_name(void);

       [[deprecated]] char *getwd(char buf[PATH_MAX]);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       get_current_dir_name():
           _GNU_SOURCE

       getwd():
           Since glibc 2.12:
               (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
                   || /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE
           Before glibc 2.12:
               _BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION

       These  functions  return  a null-terminated string containing an absolute pathname that is
       the current working directory of the calling process.  The pathname  is  returned  as  the
       function result and via the argument buf, if present.

       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 length of the absolute pathname of the current  working  directory,  including  the
       terminating  null  byte, exceeds size bytes, NULL is returned, and errno is set to ERANGE;
       an application should check for this error, and allocate a larger buffer if necessary.

       As an extension to the  POSIX.1-2001  standard,  glibc's  getcwd()  allocates  the  buffer
       dynamically  using  malloc(3)  if buf is NULL.  In this case, the allocated buffer has the
       length size unless size is zero, when buf is allocated as big as  necessary.   The  caller
       should free(3) the returned buffer.

       get_current_dir_name() will malloc(3) an array big enough to hold the absolute pathname of
       the current working directory.  If the environment variable PWD is set, and its  value  is
       correct, then that value will be returned.  The caller should free(3) the returned buffer.

       getwd()  does  not malloc(3) any memory.  The buf argument should be a pointer to an array
       at least PATH_MAX bytes long.  If the length of  the  absolute  pathname  of  the  current
       working  directory,  including  the terminating null byte, exceeds PATH_MAX bytes, NULL is
       returned, and errno is set to ENAMETOOLONG.  (Note that on some systems, PATH_MAX may  not
       be  a  compile-time  constant;  furthermore,  its  value may depend on the filesystem, see
       pathconf(3).)  For portability and security reasons, use of getwd() is deprecated.

RETURN VALUE

       On success, these functions return a pointer to a string containing the  pathname  of  the
       current  working directory.  In the case of getcwd() and getwd() this is the same value as
       buf.

       On failure, these functions return NULL, and errno is set  to  indicate  the  error.   The
       contents of the array pointed to by buf are undefined on error.

ERRORS

       EACCES Permission to read or search a component of the filename was denied.

       EFAULT buf points to a bad address.

       EINVAL The size argument is zero and buf is not a null pointer.

       EINVAL getwd(): buf is NULL.

       ENAMETOOLONG
              getwd():  The size of the null-terminated absolute pathname string exceeds PATH_MAX
              bytes.

       ENOENT The current working directory has been unlinked.

       ENOMEM Out of memory.

       ERANGE The size argument is less than the length of the absolute pathname of  the  working
              directory,  including  the  terminating  null  byte.  You need to allocate a bigger
              array and try again.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────┬───────────────┬─────────────┐
       │Interface                                                  │ Attribute     │ Value       │
       ├───────────────────────────────────────────────────────────┼───────────────┼─────────────┤
       │getcwd(), getwd()                                          │ Thread safety │ MT-Safe     │
       ├───────────────────────────────────────────────────────────┼───────────────┼─────────────┤
       │get_current_dir_name()                                     │ Thread safety │ MT-Safe env │
       └───────────────────────────────────────────────────────────┴───────────────┴─────────────┘

VERSIONS

       POSIX.1-2001 leaves the behavior of getcwd() unspecified if buf is NULL.

       POSIX.1-2001 does not define any errors for getwd().

VERSIONS

   C library/kernel differences
       On Linux, the kernel provides a getcwd() system call, which  the  functions  described  in
       this  page  will use if possible.  The system call takes the same arguments as the library
       function of the same name, but is limited to returning at most  PATH_MAX  bytes.   (Before
       Linux  3.12,  the limit on the size of the returned pathname was the system page size.  On
       many architectures, PATH_MAX and the system page size are  both  4096  bytes,  but  a  few
       architectures  have  a  larger  page  size.)  If the length of the pathname of the current
       working directory  exceeds  this  limit,  then  the  system  call  fails  with  the  error
       ENAMETOOLONG.   In  this  case,  the library functions fall back to a (slower) alternative
       implementation that returns the full pathname.

       Following a change in Linux 2.6.36, the pathname returned by the getcwd() system call will
       be prefixed with the string "(unreachable)" if the current directory is not below the root
       directory of the current process (e.g., because the process  set  a  new  filesystem  root
       using  chroot(2) without changing its current directory into the new root).  Such behavior
       can also be caused by an unprivileged user by changing the current directory into  another
       mount  namespace.   When  dealing  with  pathname  from  untrusted sources, callers of the
       functions described in this page should consider checking whether  the  returned  pathname
       starts  with  '/'  or  '('  to  avoid  misinterpreting  an  unreachable path as a relative
       pathname.

STANDARDS

       getcwd()
              POSIX.1-2008.

       get_current_dir_name()
              GNU.

       getwd()
              None.

HISTORY

       getcwd()
              POSIX.1-2001.

       getwd()
              POSIX.1-2001, but marked LEGACY.  Removed in POSIX.1-2008.  Use getcwd() instead.

       Under Linux, these functions make use of the getcwd() system call (available  since  Linux
       2.1.92).   On older systems they would query /proc/self/cwd.  If both system call and proc
       filesystem are missing, a generic implementation is called.  Only in that case  can  these
       calls fail under Linux with EACCES.

NOTES

       These  functions  are often used to save the location of the current working directory for
       the purpose of returning to it later.  Opening the current  directory  (".")  and  calling
       fchdir(2)  to  return  is usually a faster and more reliable alternative when sufficiently
       many file descriptors are available, especially on platforms other than Linux.

BUGS

       Since the Linux 2.6.36 change that added "(unreachable)" in  the  circumstances  described
       above,  the glibc implementation of getcwd() has failed to conform to POSIX and returned a
       relative pathname when the API contract requires an absolute pathname.   With  glibc  2.27
       onwards  this  is  corrected;  calling  getcwd()  from  such a pathname will now result in
       failure with ENOENT.

SEE ALSO

       pwd(1), chdir(2), fchdir(2), open(2), unlink(2), free(3), malloc(3)