SUMMARY:
When using the passthru(command, outputresult) function, and passing 'command' an uninitialized variable, Apache for Win32 will crash, and restart.

HOW IT HAPPENED:
During development of an image gallery, I was using passthru() to run ImageMagick Mogrify.exe to scale thumbnails.  I was using the variable $mogcommand to keep the shell command to use in passthru(), and $outputresult to store the result. I made a typo in $mogcommand ($mogcomand), and when testing the page in my browser, Apache for Win32 crashed, and restarted.  The $mogcomand variable was not initialized or previously used.

REPRODUCIBLE?
Yes.  Anytime I pass an unitialized variable to the shell command parameter of passthru(), the Apache server will crash and restart.

STABILITY / INSTALLATION QUALITY?
So far, perfect.  Any problems other than this have been a result of my own misconfiguration.  I have used passthru() many times on this server with no problems, provided I pass a valid variable to it.  I believe this is a valid bug.

ENVIRONMENT TYPE:
Development/testing server

SOFTWARE ENVIRONMENT:
Windows 2000 Professional
Apache 1.3.26 for Win32
PHP 4.2.3 for Win32 (MODULE)

HARDWARE ENVIRONMENT:
Pentium II/400 Mhz
128MB PC-100 SDRAM
8GB Maxtor ATA-66 Hard Drive

POSSIBLE SOLUTION:
Check if the variable passed to the shell command parameter of passthru() is initialized, and if not, generate the appropriate warning/error message.