"system" returns different exit code than running the command from the command line

greenmoss has asked for the wisdom of the Perl Monks concerning the following question:

I have this in a script:

my $code = system(q{apt-get -qq -o 'Debug::NoLocking=true' --simulate 
+upgrade});
print "code: ";
print ($code & 127);
print ";\n";
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It returns 0 exit code:

code: 0;
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But the command, run manually from the command line produces exit code 100:

$ apt-get -qq -o 'Debug::NoLocking=true' --simulate upgrade
E: Unmet dependencies. Try using -f.
$ echo $?
100
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Why is this? How do I get the "real" return code?

Comment on "system" returns different exit code than running the command from the command line Select or Download Code

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Re: "system" returns different exit code than running the command from the command line by moritz (Cardinal) on Jun 04, 2008 at 18:12 UTC
quoting perldoc system: The return value is the exit status of the program as returned by the "wait" call. To get the actual exit value, shift right by eight And farther down: `printf "child exited with value %d\n", $? >> 8;` Is there any way the documentation could be clearer about it?	[reply] [d/l]
Re^2: "system" returns different exit code than running the command from the command line by greenmoss (Novice) on Jun 04, 2008 at 18:36 UTC
Oh, I get it... I thought the "$code & 127" did the bit shifting. Blinders on I guess. Thanks.	[reply]