PHP常用系统函数

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chdir()	Changes the current directory
chroot()	Changes the root directory
closedir()	Closes a directory handle
dir()	Returns an instance of the Directory class
getcwd()	Returns the current working directory
opendir()	Opens a directory handle
readdir()	Returns an entry from a directory handle
rewinddir()	Resets a directory handle
scandir()	Returns an array of files and directories of a specified directory

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debug_backtrace()	Generates a backtrace
debug_print_backtrace()	Prints a backtrace
error_clear_last()	Clears the last error
error_get_last()	Returns the last error that occurred
error_log()	Sends an error message to a log, to a file, or to a mail account
error_reporting()	Specifies which errors are reported
restore_error_handler()	Restores the previous error handler
restore_exception_handler()	Restores the previous exception handler
set_error_handler()	Sets a user-defined error handler function
set_exception_handler()	Sets a user-defined exception handler function
trigger_error()	Creates a user-level error message
user_error()	Alias of trigger_error()
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basename()	Returns the filename component of a path
chgrp()	Changes the file group
chmod()	Changes the file mode
chown()	Changes the file owner
clearstatcache()	Clears the file status cache
copy()	Copies a file
delete()	See unlink()
dirname()	Returns the directory name component of a path
disk_free_space()	Returns the free space of a filesystem or disk
disk_total_space()	Returns the total size of a filesystem or disk
diskfreespace()	Alias of disk_free_space()
fclose()	Closes an open file
feof()	Checks if the "end-of-file" (EOF) has been reached for an open file
fflush()	Flushes buffered output to an open file
fgetc()	Returns a single character from an open file
fgetcsv()	Returns a line from an open CSV file
fgets()	Returns a line from an open file
fgetss()	Deprecated from PHP 7.3. Returns a line from an open file - stripped from HTML and PHP tags
file()	Reads a file into an array
file_exists()	Checks whether or not a file or directory exists
file_get_contents()	Reads a file into a string
file_put_contents()	Writes data to a file
fileatime()	Returns the last access time of a file
filectime()	Returns the last change time of a file
filegroup()	Returns the group ID of a file
fileinode()	Returns the inode number of a file
filemtime()	Returns the last modification time of a file
fileowner()	Returns the user ID (owner) of a file
fileperms()	Returns the file's permissions   '
filesize()	Returns the file size
filetype()	Returns the file type
flock()	Locks or releases a file
fnmatch()	Matches a filename or string against a specified pattern
fopen()	Opens a file or URL
fpassthru()	Reads from the current position in a file - until EOF, and writes the result to the output buffer
fputcsv()	Formats a line as CSV and writes it to an open file
fputs()	Alias of fwrite()
fread()	Reads from an open file (binary-safe)
fscanf()	Parses input from an open file according to a specified format
fseek()	Seeks in an open file
fstat()	Returns information about an open file
ftell()	Returns the current position in an open file
ftruncate()	Truncates an open file to a specified length
fwrite()	Writes to an open file (binary-safe)
glob()	Returns an array of filenames / directories matching a specified pattern
is_dir()	Checks whether a file is a directory
is_executable()	Checks whether a file is executable
is_file()	Checks whether a file is a regular file
is_link()	Checks whether a file is a link
is_readable()	Checks whether a file is readable
is_uploaded_file()	Checks whether a file was uploaded via HTTP POST
is_writable()	Checks whether a file is writable
is_writeable()	Alias of is_writable()
lchgrp()	Changes the group ownership of a symbolic link
lchown()	Changes the user ownership of a symbolic link
link()	Creates a hard link
linkinfo()	Returns information about a hard link
lstat()	Returns information about a file or symbolic link
mkdir()	Creates a directory
move_uploaded_file()	Moves an uploaded file to a new location
parse_ini_file()	Parses a configuration file
parse_ini_string()	Parses a configuration string
pathinfo()	Returns information about a file path
pclose()	Closes a pipe opened by popen()
popen()	Opens a pipe
readfile()	Reads a file and writes it to the output buffer
readlink()	Returns the target of a symbolic link
realpath()	Returns the absolute pathname
realpath_cache_get()	Returns realpath cache entries
realpath_cache_size()	Returns realpath cache size
rename()	Renames a file or directory
rewind()	Rewinds a file pointer
rmdir()	Removes an empty directory
set_file_buffer()	Alias of stream_set_write_buffer(). Sets the buffer size for write operations on the given file
stat()	Returns information about a file
symlink()	Creates a symbolic link
tempnam()	Creates a unique temporary file
tmpfile()	Creates a unique temporary file
touch()	Sets access and modification time of a file
umask()	Changes file permissions for files
unlink() deletes a file

下面来看一些常用的函数的返回结果

可以执行系统命令的四个函数

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shell_exec()
exec()
passthru()
system

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getcwd()返回当前目录

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file_exists()查看是否存在文件。

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pathinfo()查看文件详细信息，但是无返回，我们vardump()来看返回值。

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popen()两个参数，前面为bash命令，后面是打开模式，我们这里读取，r

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is_uploaded_file()查看是否为http post上传的文件

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file_get_contents()读取文件到字符串中。

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fgets()读取一行，应该是被禁用了。

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所以我们可以先尝试修改权限

chmod()需要两个参数

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chmod('123456.php', 0777)

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查看文件所有者fileowner()

然后就可以修改文件所有者

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chown(文件)修改文件所有者。

还有很重要的syslog()函数，先不举例了。

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这个竟然没有禁用，，直接目录全穿。scandir()打印详细目录。

一些ftp函数

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<?php
// connect and login to FTP server
$ftp_server = "ftp.example.com";
$ftp_conn = ftp_connect($ftp_server) or die("Could not connect to $ftp_server");
$login = ftp_login($ftp_conn, $ftp_username, $ftp_userpass);

$command = "ls-al > somefile.txt";

// execute command
if (ftp_exec($ftp_conn,$command))
  {
  echo "$command executed successfully.";
  }
else
  {
  echo "Execution of $command failed.";
  }

// close connection
ftp_close($ftp_conn);
?>

这是ftp_exec()执行函数，用来ftp远程连接后执行命令的函数，需要两个参数，套接字和命令。

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<?php
// connect and login to FTP server
$ftp_server = "ftp.example.com";
$ftp_conn = ftp_connect($ftp_server) or die("Could not connect to $ftp_server");
$login = ftp_login($ftp_conn, $ftp_username, $ftp_userpass);

$file = "php/test.txt";

// Try to set read and write for owner and read for everybody else
if (ftp_chmod($ftp_conn, 0644, $file) !== false)
  {
  echo "Successfully chmoded $file to 644.";
  }
else
  {
  echo "chmod failed.";
  }

// close connection
ftp_close($ftp_conn);
?>

这是ftp_chmod()函数，三个参数，套接字，权限，文件，用于修改远程文件权限。

curl命令集合

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﹤?php
// 初始化一个 cURL 对象
$curl = curl_init();

// 设置你需要抓取的URL
curl_setopt($curl, CURLOPT_URL, 'http://www.cmx8.cn');

// 设置header
curl_setopt($curl, CURLOPT_HEADER, 1);

// 设置cURL 参数，要求结果保存到字符串中还是输出到屏幕上。
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);

// 运行cURL，请求网页
$data = curl_exec($curl);

// 关闭URL请求
curl_close($curl);

// 显示获得的数据
var_dump($data);

?>

可以看到这里就是套接字的连接。