popen

(PHP 4, PHP 5)

popen — Opens process file pointer

Description

resource popen ( string $command , string $mode )
Opens a pipe to a process executed by forking the command given by command.

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Parameters

command
The command

mode
The mode

Return Values

Returns a file pointer identical to that returned by fopen(), except that it is unidirectional (may only be used for reading or writing) and must be closed with pclose(). This pointer may be used with fgets(), fgetss(), and fwrite(). When the mode is 'r', the returned file pointer equals to the STDOUT of the command, when the mode is 'w', the returned file pointer equals to the STDIN of the command.

If an error occurs, returns FALSE.

Examples

Example #1 popen() example

<?php
$handle = popen("/bin/ls", "r");
?>
If the command to be executed could not be found, a valid resource is returned. This may seem odd, but makes sense; it allows you to access any error message returned by the shell:

Example #2 popen() example

<?php
error_reporting(E_ALL);

/* Add redirection so we can get stderr. */
$handle = popen('/path/to/executable 2>&1', 'r');
echo "'$handle'; " . gettype($handle) . "\n";
$read = fread($handle, 2096);
echo $read;
pclose($handle);
?>
Notes

Note:

If you're looking for bi-directional support (two-way), use proc_open().

Note: When safe mode is enabled, you can only execute files within the safe_mode_exec_dir. For practical reasons, it is currently not allowed to have .. components in the path to the executable.

Warning
With safe mode enabled, the command string is escaped with escapeshellcmd(). Thus, echo y | echo x becomes echo y \| echo x.

See Also

pclose() - Closes process file pointer
fopen() - Opens file or URL
proc_open() - Execute a command and open file pointers for input/output

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