readlink - PHP code example

Using the Built-In Functions of PHP

PHP has many built-in functions right out of the box that can do a variety of tasks. There are functions for arrays, math, internationalization, and more. These functions allow you to quickly and easily perform common programming tasks. Using these functions can help you avoid writing your own code and save time.

In PHP, unless you explicitly tell a function to return an array by reference, it will return a copy of the array instead. Therefore, it is important to carefully read the documentation for each function to know whether it will return a value or a copy of an array.

Using the PHP header() function is an effective way to add a custom HTTP header in your code. The function accepts a string as a parameter and can be used to display or overwrite any existing headers. The function must be called before any output is sent to the browser, including HTML tags and blank lines in files or PHP scripts.

The is_link() function in PHP checks if a filename is a symbolic link. It takes one mandatory parameter, the path of the file to check. The function will return TRUE if the filename exists and is a symbolic link, FALSE otherwise.

The readlink() function is a simple and powerful tool for working with symbolic links in your PHP code. The function is similar to the C readlink() function and returns the contents of the path of a symbolic link on success, or false on error. The function fails if the path is not a symlink (except on Windows, where the normalized path will be returned).

readlink example

if (!($major && $minor)) {
            return $glibc = '';
        }

        return $glibc = "glibc{$major}.{$minor}";
    }

    function _readGlibCVersionFromSymlink($file)
    {
        $versions = array();
        if (@is_link($file)
            && (preg_match('/^libc-(.*)\.so$/', basename(readlink($file)), $matches))
        ) {
            $versions = explode('.', $matches[1]);
        }
        return $versions;
    }

    function _readGlibCVersionFromFeaturesHeaderFile()
    {
        $features_header_file = '/usr/include/features.h';
        if (!(@file_exists($features_header_file)

$v_reduced_filename = $this->_pathReduction($p_stored_filename);

        if (strlen($v_reduced_filename) > 99) {
            if (!$this->_writeLongHeader($v_reduced_filename, false)) {
                return false;
            }
        }

        $v_linkname = '';
        if (@is_link($p_filename)) {
            $v_linkname = readlink($p_filename);
        }

        if (strlen($v_linkname) > 99) {
            if (!$this->_writeLongHeader($v_linkname, true)) {
                return false;
            }
        }

        $v_info = lstat($p_filename);
        $v_uid = sprintf("%07s", DecOct($v_info[4]));
        $v_gid = sprintf("%07s", DecOct($v_info[5]));

throw new \RuntimeException("Directory $dest could not be created");
      }
      $handle = opendir($src);
      while ($file = readdir($handle)) {
        if ($file != "." && $file != "..") {
          $this->copyRecursive("$src/$file", "$dest/$file");
        }
      }
      closedir($handle);
    }
    elseif (is_link($src)) {
      symlink(readlink($src), $dest);
    }
    elseif (!copy($src, $dest)) {
      throw new \RuntimeException("File $src could not be copied to $dest");
    }

    // Set permissions for the directory or file.     if (!is_link($dest)) {
      if (is_dir($dest)) {
        $mode = FileSystem::CHMOD_DIRECTORY;
      }
      else {

$file = $this->workspace.\DIRECTORY_SEPARATOR.'file';
        $link = $this->workspace.\DIRECTORY_SEPARATOR.'link';

        // $file does not exist right now: creating "broken" links is a wanted feature         $this->filesystem->symlink($file, $link);

        $this->assertTrue(is_link($link));

        // Create the linked file AFTER creating the link         touch($file);

        $this->assertEquals($file, readlink($link));
    }

    /** * @depends testSymlink */
    public function testRemoveSymlink()
    {
        $this->markAsSkippedIfSymlinkIsMissing();

        $link = $this->workspace.\DIRECTORY_SEPARATOR.'link';

if ($copyOnWindows) {
                $this->mirror($originDir, $targetDir);

                return;
            }
        }

        $this->mkdir(\dirname($targetDir));

        if (is_link($targetDir)) {
            if (readlink($targetDir) === $originDir) {
                return;
            }
            $this->remove($targetDir);
        }

        if (!self::box('symlink', $originDir, $targetDir)) {
            $this->linkException($originDir, $targetDir, 'symbolic');
        }
    }

    /** * Creates a hard link, or several hard links to a file. * * @param string|string[] $targetFiles The target file(s) * * @return void * * @throws FileNotFoundException When original file is missing or not a file * @throws IOException When link fails, including if link already exists */

if (\is_string($options['verify'])) {
                    // Throw an error if the file/folder/link path is not valid or doesn't exist.                     if (!\file_exists($options['verify'])) {
                        throw new \InvalidArgumentException("SSL CA bundle not found: {$options['verify']}");
                    }
                    // If it's a directory or a link to a directory use CURLOPT_CAPATH.                     // If not, it's probably a file, or a link to a file, so use CURLOPT_CAINFO.                     if (
                        \is_dir($options['verify'])
                        || (
                            \is_link($options['verify']) === true
                            && ($verifyLink = \readlink($options['verify'])) !== false
                            && \is_dir($verifyLink)
                        )
                    ) {
                        $conf[\CURLOPT_CAPATH] = $options['verify'];
                    } else {
                        $conf[\CURLOPT_CAINFO] = $options['verify'];
                    }
                }
            }
        }