A brief introduction to the troubleshooting method for PHP exec () functions without return values (recommended)

The following small series will bring you an article on the PHP exec () function no return value troubleshooting method (mandatory ). I think this is quite good. now I will share it with you and give you a reference. Let's take a look at the following small series for you to discuss the PHP exec () function no return value troubleshooting method (mandatory ). I think this is quite good. now I will share it with you and give you a reference. Let's take a look at it with Xiaobian.

Exec is required for security imagemagic. many servers fail to be installed.

Exec () failed to execute the external command, but there was no error message.

Exec executes a command in the command line, but an error occurs in php. This issue is 99.99% related to permissions, but the command executed by exec will not return an error. One trick is to use the pipeline command. assume that your exec call is as follows:

Exec ('convert a.jpg B .jpg ', $ output, $ return_val );

You can change it as follows:

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

Use2> & 1The command will output the error of shell execution to the $ output variable, and output the variable for analysis.

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

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

The above is a brief introduction to the details of the PHP exec () function troubleshooting method without return values (recommended). For more information, see other related articles in the first PHP community!