Get information about, and manipulate symbolic links. More...

#include <SymLink.h>

Inheritance diagram for casa::SymLink:

Public Member Functions
	SymLink ()
	The default constructor creates a SymLink with path ".".
	SymLink (const Path &name)
	Create a SymLink with the given path.
	SymLink (const String &name)
	SymLink (const File &name)
	SymLink (const SymLink &that)
	Copy constructor (copy semantics).
	~SymLink ()
SymLink &	operator= (const SymLink &that)
	Assignment (copy semantics).
void	create (const Path &target, Bool overwrite=True)
	Make a symbolic link to a file given by target.
void	create (const String &target, Bool overwrite=True)
void	copy (const Path &target, Bool overwrite=True) const
	Copy the symlink to the target path using the system command cp.
void	copy (const String &target, Bool overwrite=True) const
void	move (const Path &target, Bool overwrite=True)
	Move the symlink to the target path using the system command mv.
void	move (const String &target, Bool overwrite=True)
void	remove ()
	Remove a symbolic link.
Path	readSymLink () const
	Read value of a symbolic link and return it as a Path.
Path	followSymLink () const
	As readSymLink, but the entire symlink chain is followed when the symlinks points to other symlinks.
Private Member Functions
void	checkPath () const
	Check if the path of the file is valid.
String	getSymLink () const
	Get the value of the symlink.

Detailed Description

Get information about, and manipulate symbolic links.

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25

<h3>Intended use:</h3> Public interface

Prerequisite

Basic knowledge of the UNIX file system
File

Etymology

The class SymLink handles SYMbolic LINKs in the file system.

Synopsis

SymLink provides functions to manipulate and to get information about symbolic links. The functions for getting information (like ownership, dates) about symbolic links are inherited from the File class.
The class SymLink itself provides functions to create, remove, copy, and move symbolic links. There is a function readSymLink which reads a link and then returns a path and there is a function followSymLink which reads a link recursively. If the link eventually refers to itself (a loop), an exception will be thrown.

Example

       SymLink symLink1("isLink");
       SymLink symLink2("isLink2");
       SymLink symLinkA("A");
       SymLink symLinkB("B");
   
       symLink1.create("~", True);    // Create a symbolic link to the home
                                      // directory. When it exists it will be
                                      // overwritten.
       symLink2.create("isLink", False); // Create a symbolic link to 
                                         // isLink. When it exists it will not
                                         // be overwritten.
       symLinkA.create(Path("B"));    // Create a recursive link
       symLinkB.create(Path("A"));    // Create a recursive link
   
       cout << symLink1.readSymLink() << endl;  // The homedirectory is printed
       cout << symLink2.readSymLink() << endl;  // isLink is printed
       cout << symLink2.followSymLink() << endl;// The homedirectory is printed
       cout << symLinkA.readSymLink() << endl;  // B is printed
       cout << symLinkA.followSymLink() << endl;// An exception is thrown (loop)

Motivation

Provide functions for manipulating and getting information about symbolic links.

Definition at line 100 of file SymLink.h.

Constructor & Destructor Documentation

casa::SymLink::SymLink ( )

The default constructor creates a SymLink with path ".".

casa::SymLink::SymLink ( const Path & name )

Create a SymLink with the given path.

An exception is thrown if the path exist and is no symbolic link or if it does not exist, but cannot be created.

casa::SymLink::SymLink ( const String & name )

casa::SymLink::SymLink ( const File & name )

casa::SymLink::SymLink ( const SymLink & that )

Copy constructor (copy semantics).

casa::SymLink::~SymLink ( )

Member Function Documentation

void casa::SymLink::checkPath ( ) const [private]

Check if the path of the file is valid.

Also resolve possible symlinks.

void casa::SymLink::copy	(	const Path &	target,
		Bool	overwrite = `True`
	)		const

Copy the symlink to the target path using the system command cp.

The target path can be a directory or a file (as in cp). An exception is thrown if:
- the target directory is not writable
- or the target file already exists and overwrite==False
- or the target file already exists and is not writable

Referenced by copy().

void casa::SymLink::copy	(	const String &	target,
		Bool	overwrite = `True`
	)		const `[inline]`

Definition at line 192 of file SymLink.h.

References copy().

void casa::SymLink::create	(	const Path &	target,
		Bool	overwrite = `True`
	)

Make a symbolic link to a file given by target.

An exception will be thrown if:
-target already exists and is no symlink
-or target already exists and overwrite==False

Referenced by create().

void casa::SymLink::create	(	const String &	target,
		Bool	overwrite = `True`
	)		`[inline]`

Definition at line 188 of file SymLink.h.

References create().

Path casa::SymLink::followSymLink ( ) const

As readSymLink, but the entire symlink chain is followed when the symlinks points to other symlinks.

An exception is thrown if this results in a loop (that is, if more than 25 links are encountered).

String casa::SymLink::getSymLink ( ) const [private]

Get the value of the symlink.

void casa::SymLink::move	(	const Path &	target,
		Bool	overwrite = `True`
	)

Move the symlink to the target path using the system command mv.

The target path can be a directory or a file (as in mv). An exception is thrown if:
- the target directory is not writable
- or the target file already exists and overwrite==False
- or the target file already exists and is not writable

Referenced by move().

void casa::SymLink::move	(	const String &	target,
		Bool	overwrite = `True`
	)		`[inline]`

Definition at line 196 of file SymLink.h.

References move().

SymLink& casa::SymLink::operator= ( const SymLink & that )

Assignment (copy semantics).

Path casa::SymLink::readSymLink ( ) const

Read value of a symbolic link and return it as a Path.

If the symlink does not exist, an exception will be thrown. When the symlink points to a file with a relative name, the resulting file name gets prepended by the dirname of the symlink, which is similar to the way a shell handles symlinks. E.g.

         ls > subdir/a
         ln -s a subdir/b
         more subdir/b

The more command shows the results of subdir/a.

void casa::SymLink::remove ( )

Remove a symbolic link.

The documentation for this class was generated from the following file:

casacore/casa/OS/SymLink.h

Public Member Functions

Private Member Functions