REALPATH(3) Library Functions Manual REALPATH(3)

realpath — resolve a pathname


#include <stdlib.h>

char *realpath(const char *restrict file_name,
       char *restrict resolved_name);

The realpath () function shall derive, from the pathname pointed to by , 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.

Upon successful completion, realpath () shall return a pointer to the resolved name. Otherwise, realpath () shall return a null pointer and set to indicate the error, and the contents of the buffer pointed to by resolved_name are undefined.

The realpath () function shall fail if:

Read or search permission was denied for a component of file_name .
Either the file_name or resolved_name argument is a null pointer.
An error occurred while reading from the file system.
A loop exists in symbolic links encountered during resolution of the path argument.
The length of the file_name argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.
A component of file_name does not name an existing file or file_name points to an empty string.
A component of the path prefix is not a directory.

The realpath () function may fail if:

More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.
Insufficient storage space is available.

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

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


ptr = realpath(symlinkpath, actualpath);

None.

None.

None.

getcwd(3) , sysconf(3) , the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <stdlib.h>

First released in Issue 4, Version 2.

Moved from X/OPEN UNIX extension to BASE.

The keyword is added to the realpath () prototype for alignment with the ISO/IEC 9899:1999 (“ISO C99”) standard.

The wording of the mandatory [ELOOP] error condition is updated, and a second optional [ELOOP] error condition is added.

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December 6, 2001 posix.fail