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Manuál Linux
[Linux manuál]

realpath: vyřešit cestu

Originální popis anglicky: realpath - resolve a pathname

Návod, kniha: POSIX Programmer's Manual


#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 file_name, 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.
If resolved_name is a null pointer, the behavior of realpath() is implementation-defined.


Upon successful completion, realpath() shall return a pointer to the resolved name. Otherwise, realpath() shall return a null pointer and set errno 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.
The file_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 sections are informative.


Generating an Absolute Pathname

The following example generates an absolute pathname for the file identified by the symlinkpath argument. The generated pathname is stored in the actualpath array.
#include <stdlib.h> ... char *symlinkpath = "/tmp/symlink/file"; char actualpath [PATH_MAX+1]; char *ptr;
ptr = realpath(symlinkpath, actualpath);




Since the maximum pathname length is arbitrary unless {PATH_MAX} is defined, an application generally cannot supply a resolved_name buffer with size {{PATH_MAX}+1}.


In the future, passing a null pointer to realpath() for the resolved_name argument may be defined to have realpath() allocate space for the generated pathname.


getcwd() , sysconf() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h> Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
2003 IEEE/The Open Group
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