There is no problem with the exec function in Windows environment, but the return value cannot be negative in Linux.
string exec ( string $command [, array &$output [, int &$return_var ]] )
The third parameter, why can’t it receive negative numbers??
The &$return_var here is the program return value. At first, my answer was that it can be a negative number.
Generally in C language we would write like this
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| 代码如下 |
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#include
#include
int main()
{
printf("^_^n");
return -5;
}
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#include
#include
int main()
{
Printf("^_^n");
Return -5;
}
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E:devphp535>php -r "exec('return.exe',$out,$a);var_dump($a);"
int(-2)
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This -5 is the return value, but it is customary to write it as 0 or 1.
Note: Many people write the main function as void main() in their C code. This is actually wrong, so I won’t go into details.
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exec("/home/wwwroot/test/rtest.out 2>&1",$out,$a);
var_dump($out,$a);
array(1) { [0]=> string(3) "^_^" } int(251)
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After compiling the above code, run it under CMD, and then you can see the output result. Then, enter "echo %ERRORLEVEL%", press Enter, and you can see the return value of the program. This %ERRORLEVEL% represents the return status of the program. It is indeed possible to be a negative number under WIN. As shown in the picture:
, php calls are also normal.
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E:devphp535>php -r "exec( 'return.exe',$out,$a);var_dump($a);"
int(-2)
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-bash-3.00$ vi main.c
-bash-3.00$ gcc -o ./mm main.c
-bash-3.00$ ll
total 48
drwxr-xr-x 3 www www 4096 May 4 2011 2011
drwxr-xr-x 6 www www 4096 Jun 23 2011 eoc
-rwxr-xr-x 1 www www 7131 Feb 1 12:47 hello
-rw-r--r-- 1 www www 3 Feb 1 12:51 hello.c
-rw-r--r-- 1 www www 99 Feb 1 12:50 main.c
-rwxr-xr-x 1 www www 4714 Feb 1 12:51 mm
drwxr-xr-x 3 www www 4096 Jun 24 2011 test
-bash-3.00$ ./mm
^_^
-bash-3.00$ echo $?
251
-bash-3.00$
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But under Linux, it is always a positive number. At first I suspected it was a permissions issue. After using chmod +x, the permissions issue was eliminated.
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| exec("/home/wwwroot/test/ rtest.out 2>&1",$out,$a);
var_dump($out,$a);
array(1) { [0]=> string(3) "^_^" } int(251)
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It looks like 256+return val. You can see that a negative number is actually returned, but it is converted into a positive number.
Then I looked at the source code in standard/exec.c, and found no clues. It was very strange, and suddenly I realized that I had forgotten a step. Forgot to look at the value returned by the program to the OS.
You can use echo $? to display the status of the last command.
| The code is as follows |
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| -bash-3.00$ vi main.c
-bash-3.00$ gcc -o ./mm main.c
-bash-3.00$ ll
total 48
drwxr-xr-x 3 www www 4096 May 4 2011 2011
drwxr-xr-x 6 www www 4096 Jun 23 2011 eoc
-rwxr-xr-x 1 www www 7131 Feb 1 12:47 hello
-rw-r--r-- 1 www www 3 Feb 1 12:51 hello.c
-rw-r--r-- 1 www www 99 Feb 1 12:50 main.c
-rwxr-xr-x 1 www www 4714 Feb 1 12:51 mm
drwxr-xr-x 3 www www 4096 Jun 24 2011 test
-bash-3.00$ ./mm
^_^
-bash-3.00$ echo $?
251
-bash-3.00$
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This way you can see what value exec returns to the OS.
Under Linux, this return value is an unsigned type and returns a positive number, so it is also a positive number when passed to PHP. PHP is actually the value returned by the exec call.
exec directory operation
2down vote For greater control over how the child process will be executed, you can use the proc_open() function:
2 down vote
For greater control over how the child process will be executed, you can use the proc_open() function:
The code is as follows
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$cmd = 'Scripts/script.sh';
$cwd = 'Scripts';
$spec = array(
// can something more portable be passed here instead of /dev/null?
0 => array('file', '/dev/null', 'r'),
1 => array('file', '/dev/null', 'w'),
2 => array('file', '/dev/null', 'w'),
);
$ph = proc_open($cmd, $spec, $pipes, $cwd);
if ($ph === FALSE) {
// open error
}
// If we are not passing /dev/null like above, we should close
// our ends of any pipes to signal that we're done. Otherwise
// the call to proc_close below may block indefinitely.
foreach ($pipes as $pipe) {
@fclose($pipe);
}
// will wait for the process to terminate
$exit_code = proc_close($ph);
if ($exit_code !== 0) {
// child error
}
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$cmd = 'Scripts/script.sh';
$cwd = 'Scripts';
$spec = array(
// can something more portable be passed here instead of /dev/null?
0 => array('file', '/dev/null', 'r'),
1 => array('file', '/dev/null', 'w'),
2 => array('file', '/dev/null', 'w'),
);
$ph = proc_open($cmd, $spec, $pipes, $cwd);
if ($ph === FALSE) {
// open error
}
// If we are not passing /dev/null like above, we should close
// our ends of any pipes to signal that we're done. Otherwise
// the call to proc_close below may block indefinitely.
foreach ($pipes as $pipe) {
}
// will wait for the process to terminate
$exit_code = proc_close($ph);
if ($exit_code !== 0) {
// child error
}
http://www.bkjia.com/PHPjc/632187.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632187.htmlTechArticleThere is no problem with the exec function in the Windows environment, but the return value cannot be a negative number in Linux. string exec ( string $command [, array $output [, int $return_var ]] ) The third parameter...
