Paul, you are wrong, if you think backticks and system calls are the same things...
You should read more docs.

perlfaq8 - Why can't I get the output of a command with system?
"You're confusing the purpose of system() and backticks (``). system() runs a command and returns exit status information (as a 16 bit value: the low 7 bits are the signal the process died from, if any, and the high 8 bits are the actual exit value). Backticks (``) run a command and return what it sent to STDOUT."

perlfaq8 - What's wrong with using backticks in a void context?
"Backticks are one; they collect the output from the command for use in your program. The system function is another; it doesn't do this."

perlfaq8 - What's wrong with using backticks in a void context?
"And now they think ``Hey, I'll just always use backticks to run programs.'' Bad idea: backticks are for capturing a program's output; the system function is for running programs."

System compatiblity:
ActivePerl-Winfaq5
"* system() or backtick (``) calls to system tools that aren't available on ActivePerl."

Finally about performance issues, if somebody use mod_perl (!):
Spawning a Detachable Sub-Process
"Just like with fork(), using the system call system() defeats the whole idea behind mod_perl. The Perl interpreter and modules would be loaded again for this external program to run if it's a Perl program. Remember that the backticks (`program`) and qx(program) variants of system() behave in the same way."

Efficiency in Perl
"CGI scripts, such as the ones using system() (which also reduces portability) or `backtick` notation are inefficient by their very nature, and very resource-intensive. There are ways to reduce or eliminate all these overheads, but these tend to be operating system- or server-specific (for which the best support seems to be in Apache)."


P.S.: Sorry, my post seems offtopic, it's not related to "displaying Thumbnail" in any way :(

Best regards,
Webmaster33

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