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Php exec can not get the value of the solution: 1, open the corresponding PHP code file; 2, modify the code to "exec ('convert a.jpg b.jpg 2 > & 1, $output, $return_val);"

This article operating environment: Windows7 system, PHP7.4 version, Dell G3 computer.

What if php exec can't get the value?

The exec () function of PHP has no return value troubleshooting method:

Exec is required for secure imagemagic. Installation failed on many servers.

Exec () failed to execute the external command without any error message.

Exec has no problem executing a command at the command line, but there is an error in PHP. 99.99% of this problem is related to permissions, but commands executed by exec do not return an error. One trick is to use pipe commands, assuming that your exec call is as follows:

Exec ('convert a.jpg b.jpgkeeper, $output, $return_val)

You can change it as follows:

Exec ('convert a.jpg b.jpg 2 > & 1, $output, $return_val); print_r ($output)

Using 2 > & 1, the command outputs the shell execution error to the $output variable, which can be parsed.

Note: exec has three parameters, the first is the command to be executed, the second is an array, the value of the array is generated after the execution of the first command, the status of the third parameter, 0 indicates success, and the rest indicates failure.

There are three functions in php that can be used to execute the external command system,exec,passthru.

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