Description
void passthru (string command [, int
return_var])
The passthru() function is similar to the
Exec() function in that it executes a
command. If the
return_var argument is present, the return
status of the Unix command will be placed here. This function
should be used in place of Exec() or
System() when the output from the Unix command
is binary data which needs to be passed directly back to the
browser. A common use for this is to execute something like the
pbmplus utilities that can output an image stream directly. By
setting the content-type to image/gif and
then calling a pbmplus program to output a gif, you can create
PHP scripts that output images directly.
Note that if you start a program using this function and want to
leave it running in the background, you have to make sure that the
output of that program is redirected to a file or some other
output stream or else PHP will hang until the execution of the
program ends.
See also exec(), system(),
popen(), EscapeShellCmd(),
and the backtick
operator.
